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COPYRIGHT DEPOSIT. 








































































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/£ < 7(7 6 


PRACTICAL PHYSIOLOGY; 


OR, 


ANATOMY AND PHYSIOLOGY 






APPLIED TO HEALTH. 


FOR THE USE OF 



SCHOOLS AND FAMILIES. 







REVISED EDITION, WITH SEVENTY ENGRAVINGS. 



BY EDWARD JARVIS. M. D. 

•• ' 



> - 
» > •> 


PHILADELPHIA: 

THOMAS, COWPERTHWAIT & CO. 

New York, Geo. F. Cooledge & Bro.: —Boston, Phillips, Sampson & Co.: B. B. Massey 
<fc Co.; W. J. Reynolds & Co.:—Baltimore, Cushing & Bailey:—Charleston, S. C., 
McCarter <k Allen: — Louisville, Ky., Morton & Griswold; Beckwith & 
Morton:—St. Louis, Fisher <fc Bennett; Wm. D. Skillman; Amos H. 

Shultz & Co.Cincinnati, J. F. Desilver:—Nashville, Wm. T. 

Berry; Chas. W. Smith : —Memphis, C. C. Cleaves : — Lexing¬ 
ton, C. S. Bodley & Co.: - Buffalo, T. <k M. Butler. 























Gr?*>o, 

.J4- 

\%SZ 


Entered according to Act of Congress, in the year 1851, 
By Edward Jarvis, 

In the Clerk’s Office of the District Court of Massachusetts 


PRINTED BY SMITH & PETERS, 

Franklin BuildWgs, Sixth Street below Areb, I'hiladelphi* 


PREFACE. 






I 

Every human being is appointed to take the charge of his own 
body. He must supply its wants, direct its powers, regulate its 
actions, and thus sustain his life. This responsibility for the care 
of health takes precedence of all others, and requires the earliest 
attention to prepare to meet it. Before any one can have any use 
for other knowledge, he must know how to live. He should, there¬ 
fore, learn the nature and the wants of his frame, and of its various 
organs, even earlier than he studies the features of the earth, the 
science of numbers, or the structure of language; for, before he 
can put these to any practical use, he must eat, and breathe, and 
move, and think. Physiology should, then, be included among the 
subjects of all school education, and thus preparation be first made 
for the fulfilment of the first responsibility of life. 

This book has been written to aid youth and others in this prepa¬ 
ration. It is intended to be exclusively a practical work. It de¬ 
scribes only those organs, and teaches only those principles, which 
are necessary to be known for the correct management of our 
organs, the maintenance of health, and the preservation of life. 
All other anatomical and physiological matters, which, however in¬ 
teresting to the naturalist, or useful to the medical student, are not 
necessary for the government of our daily actions, are here omitted. 

With the hope that the knowledge which may be gained from 
these pages will not only excite both youth and adults to feel their 
responsibility for the care of their health and lives, but guide them 
in the discharge of it, this work is respectfully offered to the schools 
and the public. 



PREFACE TO THE REVISED EDITION. 


In order to make the principles of this book more easily under¬ 
stood, and the work more acceptable and useful, fifty-five new en¬ 
gravings are added to those which were in the former editions. 
These illustrations of the various parts and positions of the human 
body have been selected with great care, and designed by the best 
artists, with nice adaptation to the text. Several pages of an¬ 
atomical descriptions are also added to explain them. 

In doing this, the great purpose before adopted in writing this book 
has still been kept in view, — of making Anatomy entirely sub¬ 
servient to the study of Physiology, and of making Physiology sub¬ 
servient to the knowledge of its uses and applications to the affair? 
and the circumstances of life, and of holding these up as the end 
of this study. 

The great and sole object of this work is to teach the laws of life, 
the powers of the several organs, the limit of their strength, the 
way in which they are to be developed and sustained, their proper 
uses, and the certain and evil consequences that follow their mis¬ 
application. 

For these purposes, it is necessary to learn, first, the general 
structure of the organs and parts which are submitted to our man¬ 
agement ; second, the law of their being and action; and third, 
their application to, and connection with, the common affairs of life. 

The first is limited, and is only preparatory to the second. The 
second also is limited, and secondary to the third. The last is 
almost infinite in extent and variety, and requires much study. 

In sustaining the body with food, and drink, and air, — in defend¬ 
ing it with clothing and shelter, — in the use of our muscles and 
brain, — in applying the body and the mind to whatever purpose, 
we use some or all of our organs; and the health and strength, or 
pain and weakness, the good or the evil consequences, must be in 
accordance with the wisdom and faithfulness with which we govern 
ourselves in these matters. Therefore, the knowledge of the Phys¬ 
iological Laws, and of their requirements, becomes of practical im¬ 
portance in every moment, and in all the circumstances of our being. 

To all Teachers of Youth, this view of this study is respect¬ 
fully commended; and they are urged not to be led away by the 
vain hope of making the subjects of their instruction mere anatom¬ 
ical scholars, to the neglect of that practical wisdom which alone 
will avail them in the government of their lives. 

EDWARD JARVIS. 

Dorchester, Mass., November 1851. 


CONTENTS 


PART I. 

DIGESTION AND FOOD. 

Chap. Page. 

1. Food supplies the Growth and the Changes of Particles of the 

Body. — Digestive Apparatus.—Mouth... 9 

2. Saliva.—Mastication. — Pharynx. — (Esophagus. — Swallowing. 13 

3. Stomach.—Gastric Juice.—Digestion.—Beaumont’s Observations. 18 

4. Gastric Juice flows during Eating. —Measure of Food to be eaten. 

— Hunger. 24 

5. Motions of Stomach.—Heat during Digestion. — Pyloric Valve. 29 

6. Time required for Digestion of various Kinds of Food. 33 

7. Drink with Food impedes Digestion.—Effect of Bulk on Diges¬ 

tion.—Light and heavy Bread. 36 

8. Chyme. — Alimentary Canal.—Lacteals.—Chyle differs with Food. 39 

9. Man selects his Food. — Healthy Digestion comfortable. — Hun¬ 

ger needs the Attention of the Brain. 43 

10. Appetite affected by State of Mind —Not identical with digestive 

Power or Taste. 47 

11. Great Eaters. — Hunger recurs when Blood wants more Chyle. — 

Intervals between Meals.—Regular Hours of Eating best. 50 

12. Breakfast should be before Labor or Exposure. — Dinner. — 

Lunch. — Supper, injurious if late. 55 

13. Quantity of Food should be larger for the Active and Laborious.. 60 

14. Quantity of Food determined by Wants of System and digestive 

Power. — Measured thus when we eat slowly. —Excessive Food 
oppressive. — Rapid Eating. 64 

15. Appetite allowable, but not a Guide ; injurious if it governs Eating. 68 

16. Exercise before or after Eating impedes Digestion.. 74 

17. Cheerfulness at Meals. — Consequences of Abuse of digestive 

Organs. 78 

18. Animal and vegetable Food. — Climate and Season should affect 

Diet. 80 

19. Temperaments — should affect Diet... 83 

20. Food according to Difference of Constitution, Age, and Habit... 87 

21. Digestibility and Nutritiousness of Food not identical. — Condi¬ 

ments and Alcohol exhaust Sensibility of Stomach.—No Rule 
of Diet for all. 89 

PART II. 

CIRCULATION OF THE BLOOD, AND NUTRITION. 

1. Apparatus of Circulation. — Heart.—Arteries. 93 

2. Veins. — Capillaries. — Pulmonary Arteries and Veins.—Double 

Circulation. 100 

3. Power of Heart. — Valves. — Arteries. — Quantity and Flow of 

Blood varies with Circumstances, Exercise, States of Mind, and 

Feelings... 105 

1 * 




















6 


CONTENTS. 


4. Object of Eating. — All Parts of Body formed out of Blood. — 

Composition of Blood and Flesh. — Atoms of Body enjoy short 
Life, and are removed.—Absorbents. HO 

5. Nutrients and Absorbents, active in Laborer, who needs more 

Food. — Wens and Swellings.... • • 113 

6. Young and Active have new Atoms of Flesh. — Old and Inactive 

have old Atoms.—Unerring Precision of Nutrition. 117 


PART III. 

RESPIRATION. 


1. Wasted Particles carried out of the Body. — Composition of Blood 

in right Side of the Heart. — Chest. — Ribs. —Spine.. . 120 

2. Movement of Ribs. — Diaphragm. — Inspiration. — Expiration. — 

Size of expanded and contracted Chest. 123 

3. Lungs. — Organ of Voice. — Air-Vessels. — Coughing. — Respi¬ 

ration. 127 

4. Waste Particles. — Carbon. — Air. — Oxygen. —Nitrogen. — Car¬ 

bonic Acid. — Blood absorbs Oxygen from Air and gives Car¬ 
bonic Acid. 132 

5. Venous changed to arterial Blood. — Oxygen consumed, and Car¬ 

bonic Acid and other Matter given out, in Respiration. — Of¬ 
fensive Breath. 135 

6 . Respired Air unfit to be breathed again. — Air should have full 

Proportion of Oxygen.— Air loaded with Carbonic Acid or 
Water can take no more from Lungs. 138 

7. More Oxygen consumed, and Carbonic Acid given out in cold, 

than warm Air; by strong and cheerful than by consumptive 
and melancholy Persons. 141 

8 . Lungs must have Room to breathe. 114 

9. Natural Shape of Chest most beautiful. — Corresponds to Size of 

Body. 147 

10. Frequency of Respiration. — Size of Chest and Quantity of Air in¬ 

haled, correspond to the Waste to be carried away. 150 

11. Quantity of Air spoiled by Loss of Oxygen, by Carbonic Acid Gas, 

and Vapor of Lungs and of Skin. 152 

12. Want of fresh Air in Houses, Parlors, Sleeping-Rooms, Cabins.. 154 

13. Foul Air in Workshops, Churches, Public Halls and School- 

houses. — V entilation. 157 

14. Connection between Fulness of Life and Respiration..... 162 

15. Breathing foul Air creates Weariness, depreciates Life, impairs 

Constitution. — Drowning. —■ Consumption. 165 

16. Privation of Air. —Supply of Air for all Animals. —Plants give 

Oxygen, and consume Carbonic Acid Gas. 168 


PART IV. 

ANIMAL HEAT. 

1 . Animal Heat not changed by Temperature of surrounding Matter. 

— Blagden’s Experiments.°. 171 

2. Animal Heat generated within. — Warm and cold blooded Ani- 

mals. Animal Heat connected with Respiration. 174 

3. Latent and sensible Heat. — Internal Combustion. 177 

4. Animal Heat increased by Exercise. — Dependent on good*Air 

and Food. —Well-fed warmer than ill-fed. — Effects of Diet 
and Alcohol on internal Heat. 


180 
























CONTENTS. 


7 


5 . Effects of Disease, Fatigue, Age, Sleep, on Heat. — Amount of 
Heat prepared in a Day. — More in warm than cold Seasons. 
Winter and Summer Constitution... 185 


PART V. 

THE SKIN. 

1. Skin, Cuticle, thickened by Friction. — Blisters. — Corns. 191 

2. Cuticle. — Nails. — Hoof. — Horns. — Seat of Color. — True Skin 

contains perspiratory Apparatus. 194 

3. Perspiration, sensible and insensible; Quantity. 198 

4. Perspiration affected by State of Air. — Oily Excretion of Skin. — 

Effect of tight Clothing. 201 

5. Connection between Skin and Stomach, Lungs and Muscles.— 

Effect of Cold. 204 

6. Skin absorbs Food, Liquids, Medicine, Contagion, Poison. 207 

7. Sense of Touch; impaired if Skin is foul; acute in the Blind.... 210 

8. Skin regulates Heat by Perspiration.'—Sensation of Cold and 

Heat.1. 213 

9. Quantity of Clothing affected by Habit. 216 

10. Clothing, Need of, affected by Food, Digestion, Health, Air, Hab¬ 

its, Age. . 220 

11. Clothing should be loose.—Linen, Cotton, Silk, Wool. 224 

12. Flannel.—Cutaneous Excretions.—Foul Clothing. — Airing Cloth¬ 

ing and Beds. 226 

13. Bathing makes Skin soft and healthy. 230 

14. Cold Bathing. — Laborers need Bath. 233 

15. Effects of Cold Bathing on Health. — Time and Conditions of 

Bathing. 235 

16. Sense of Touch made more acute by Bathing and Friction. 238 


PART VI. 

BONES, MUSCLES, EXERCISE, AND REST. 

1. Bones, Composition of, in Childhood; in Old Age; have Blood- 

Vessels and Nerves; subject to Growth and Decay; grow 
strong by Use. 241 

2. Skeleton. — Bones.—Head. — Chest.—Spine. — Pelvis. 245 

3. Arms. — Wrist. — Hand.—Leg. — Foot. — Arch. — Shape. 250 

4. Joints. — Elbow. —Knee. — Shoulder. — Hip. — Structure. —Lig¬ 

aments. — Sprains. — Dislocations. 255 

5. Muscles, Number, Action, Description, Use. 260 

6. Muscles, Shape, Attachments, Arrangement, Action. 268 

7. Muscles, Situation, sacrifice Power, Cooperation. 274 

8. Muscles, Strength increased by Exercise. 278 

9. Muscular Strength unequal; Action increases Power in other 

Organs. 282 

10. Muscular Action strengthens Body and Mind. — Kinds of Exer¬ 

cise . 2S6 

11. Exercise adapted to Strength, Effect of, on Weak ; on Dyspeptics. 

— Gymnastic Exercises. 289 

12. Kinds of Exercise. — Walking. — Exercise of Boys; of Girls.— 

Effects of. — Habits of English and American Women. — Time 
for Exercise. 292 

13. Exercise, Place for. — Should be regular. —Needed by All. 295 

14. Labor, Limit of Power. — Proper Expenditure of Strength. 298 































8 


CONTENTS. 


15 Effect of great Efforts. —Proper Exercise of Children and Youth. 302 

16. Laborer needs healthy Organs of Digestion, Nutrition, Res¬ 

piration, and Skin. — Connection of Exercise with Brain. 304 

17. Effect of Hope and Confidence, Doubt and Fear, Cheerfulness 

and Melancholy, of Passion and Alcohol, on Strength. 307 

18. Attitudes. — Spine, supported by Muscles, very strong. — Porters. 

— Pedlers. — Burdens on Head. — Spine erect. — Centre of 
Gravity over Line of Support. 309 

19. Erect Attitude best for Walking; for Labor ; for Mechanics; 

Farmers. — Spine curved from side to side ; Bent by stooping. 

— Students, Writers have curved Spine ; and Girls more than 
Boys. 315 

20. Time for Labor. — Experiments. — Sleep, Time for; Effect of 

Loss. — Disturbed by difficult Digestion. 321 

PART VII. 

BRAIN AND NERVOUS SYSTEM. 

1. Brain. — Nervous System. — Spinal Cord.—Nerves. 325 

2. Brain connected with all Parts by Nerves; receives Impressions 

through them. — Sensations in Brain. — If Nerve is cut, Sensa¬ 
tion and Power cease. 330 

3. If Nerve is touched or diseased, Sensation is excited in the Brain. 333 

4. Pain in amputated Limbs.—Voluntary and involuntary Motion. 336 

5. All Organs and Functions impaired when Brain is impaired. — 

Brain not sensitive; subject to Growth and Decay; has large 
Supply of Blood; fatigued with Labor. 340 

6 . Day the Time for mental Labor. — Brain gains Power by Exer¬ 

cise ; weakened by Over-Action ; connected with other Organs 
— Effect of Alcohol. 344 

7. Brain Seat of Mind and Affections. — Power of Mind limited by 

Power of Brain. —Mind impaired by Indigestion, Hunger, Ex¬ 
cess of Food. — Cheerfulness favors Respiration, Digestion, and 
muscular Action. 349 

8 . Brain sustains physical and mental Actions. — Mind w r orks best 

when Body is easy. — Uncomfortable Sensations interrupt 
Study. 353 

9. Mental Action interrupted by moral Feelings, Anxiety, Fear.— 

Proper and improper Motives for Study. 357 

10. Various mental Powers affected by Education. — Precocious Chil¬ 

dren. — Effect of Study on Health. — Ill Health of literary Men. 361 

11. Inequality of Powers ; affected by Education. 364 

12. Habitual Actions easy. — Perfect Education. — Concentration of 

Mind. — Vacations. 368 

13. If Inequality of Powers be disregarded, Mind may be deranged. 

— Insanity from Misuse of Mind, Dyspepsia, Cold, Over- 
Action. 373 

14. Insanity from misdirected Education, religious Anxiety, per¬ 

verse Habits. 375 

15. Day-Dreaming, Passion, Intoxication, Fright may cause Insanity. 

— Various Grades of mental Health. — Sound Mind in sound 
Body. 377 

16. Eye. — Composition. — Tumors. — Pupil.— Effect of Light.— 

Tears. 380 

17- Near-sightedness. — Spectacles. — Far-sightedness. — Diseases of 

the Eye. — Use and Care of the Eye. 385 

18. Ear. — Structure. — Hearing. — Deafness ... 387 

Conclusion. 391 























PRACTICAL PHYSIOLOGY. 


PART I. 

DIGESTION AND FOOD. 

CHAPTER I. 

Giowthof the animal Body, and the Changes of its Particles supplied 
by Food. — Food converted into Flesh by the Digestive Apparatus 
and the Blood-Vessels. — Digestive Apparatus. — Mouth. — Teeth. 

1. The animal body increases in size and weight from 
birth to manhood. The material which supplies this growth 
is the food which we eat. Beside this, there is another de¬ 
mand for food. During the whole of life, there is an inces¬ 
sant change going on in the particles that compose the body. 
It is a law established by the Creator from the beginning, 
that life cannot continue long in animal matter. The atoms, 
which compose the living body, receive the principle of life 
when they enter their appointed places, and become apart of 
the animal frame. They retain this principle but a short 
period, and, while they retain it, they perform their part of the 
work of life. But soon their work is finished, and then they 
yield their vitality, and give up their places to other atoms, 
that come to enjoy life, and work a while, and yield and de¬ 
part, as those that went before them had done. 

2. This law of unceasing change is impressed upon all 
animal beings. In all, the particles are constantly going out 
through the skin and the lungs, and an equal quantity of 
matter must, therefore, be coming in through the mouth. If 




10 


PRACTICAL PHYSIOLOGY. 


this be not djne, and the supply be unequal to the waste, the 
animal loses flesh, and the body diminishes in weight. This 
change of particles and waste of matter differ in different 
persons, and in different circumstances, as will be shown in 
the course of this book. 

3. Here is a double necessity for the addition of matter to 
the body from without — the growth or increase of the animal 
body in its earlier years, and the waste consequent upon the 
changes of the particles through the whole period of exist¬ 
ence. The food supplies both these demands, and is there¬ 
fore necessary from the beginning to the end of life. 

4. Food is not living flesh: much that we eat — bread, 
vegetables, fruit — has not even any resemblance, in its 
appearance or character, to flesh. Yet these matters — the 
vegetables and the lifeless meats — are converted into living 
flesh; and not only so, but into many and various kinds of 
flesh, as many and as various as enter into the composition of 
the human body. All this is done in part by the digestive 
apparatus, and in part by the blood-vessels. 

5. The digestive apparatus effects the first change in the 
food; it grinds it in the mouth, dissolves it and converts it in 
the stomach into a pulpy material fit to supply the wants of 
the blood, and sends the nutritious portions to the heart. 
The blood-vessels carry this blood to all the portions of the 
body, and with this they supply the growth and the waste of 
all the organs and textures. 

6. This apparatus consists of the mouth and pharynx, the 
oesophagus or gullet, the stomach, and the alimentary canal. 
In the mouth are the lips; the teeth, the tongue, and the sali¬ 
vary glands. The pharynx lies back of the palate, between 
the mouth and the gullet. The oesophagus is a tube, that 
connects the mouth with the stomach. The stomach is a 
large sack, in which the digestive process is mostly performed. 
From the alimentary canal, the lacteals or absorbent vessels 
open. These take up the nutritious portion of the digested 
food, and carry it to the veins. Beside these organs, there 
are some others, such as the liver and the pancreas, which 


DIGESTION AND FOOD. 


11 


render some assistance in the work of digestion. All these 
organs together form the digestive apparatus, which is com¬ 
plete and perfect in itself; nothing is wanting for the work, 
and there is nothing unnecessary. Each one of these organs, 
or parts of organs, has a separate and distinct part to perform 
in the work of converting food into the nutriment of the blood. 

7. The mouth is the first and only visible organ of digestion, 
and first receives the food from our hands and our tables. It 
is composed of several parts, all of wh ; ch are employed in 
the preparatory work of digestion. The lips and the cheeks 
form the outward walls of the mouth, and retain the food 
after it is received. The teeth serve to divide and break 
down the morsel to a fineness suitable to the stomach. The 
tongue rolls the morsel about, and keeps it in its place be¬ 
tween the teeth, while it is undergoing the process of masti¬ 
cation or chewing. 

8. The teeth are the most prominent organs in the mouth. 
They differ in various animals, according to the food upon 
which they live. The carnivorous or flesh-eating animals 
have teeth fitted for seizing upon their prey, and for cutting 
up flesh. Hence they have sharp cutting or front teeth; 
and long, sharp and pointed canine or stomach and eyeteeth; 
and grindefs, with high and sharpened points, by which they 
chew or masticate their fleshy food with facility. 

9- The vegetable-eating animals have short, blunt, and 
strong front or incisor teeth, by which they break off their 
food, either grass or foliage. As they seize no prey, they 
have no use for the sharp canine or stomach and eye teeth; 
therefore these teeth are very small, and in some scarcely 
seen ; but their molar or grinding teeth are very large, broad, 
and flat. Their surface is covered with slightly-raised lines, 
to enable them to grind down their food, which requires more 
crushing than cutting. 

10. Man is neither herbivorous nor carnivorous exclu¬ 
sively, but is either or both, as occasion requires. Com¬ 
monly he is both. His food, for the most part, is a mixture 
of vegetables and flesh. He is therefore fitted with a set of 


12 


PRACTICAI PHYSIOLOGY. 


teeth partaking of the nature of each of these classes. He 
has sharp incisor teeth, but they are not so long and pointed 
as those of the dog. His grinders are not covered with points 
as prominent and sharp as those of the lion, nor are they so 
flat on the surface as those of the ox; yet they partake some¬ 
what of the character of both. He can chew either meat or 
grains, as he may desire. 


Fig. I. Teeth of one Side. 



11. Man has sixteen teeth in each jaw. The four incisor 
teeth (Fig. I. a, a) stand in front; these are broad, flat, and 
somewhat sharp : with these he can bite or cut off his morsel 
of bread, meat, &,c. Next to these are the canine teeth, 
(Fig. I. 6,) one on each side ; these are commonly called the 
stomach teeth in the lower jaw, and eye teeth in the upper 
jaw. Next to these are the bicuspid teeth , (Fig. I. c, c,) two 
on each side, with two fangs ; and behind these are the 
molar teeth , (Fig. I. d, d , c?, c, c, c,) or grinders , three on each 
side: these have three fangs, as shown in Fig. I., in the 
upper jaw, d, d , c?, and only two in the lower jaw, c, c, c. 
These have pointed elevations sufficiently sharp to cut off 
meat, and sufficiently flat to grind vegetables and grains. 

12. The teeth are firmly set in each jaw, with long fangs, 




DIGESTION AND FOOD. 


13 


so that they are not easily started from their places. They 
are composed of soft bone within, but are covered on the 
outside with an enamel of very hard texture, which admits 
of an exquisitely fine polish. This enamel comes in contact 
with the food, the drinks, and the air. It will bear great variety 
of exposure, and resist the wear of great friction. Yet, when 
the mouth is neglected, the enamel is apt to decay. If any 
of the food, which has been masticated and mixed with the 
saliva, be suffered to remain about the teeth, this mixture 
undergoes a corrupting fermentation, and acts upon the hard 
enamel. After a while, a hole is eaten through this cover¬ 
ing ; and then, when this decay reaches the softer sub¬ 
stance of the body of the teeth, it acts much more rapidly. 

13. This decay is assisted also by the gathering of the 
secretions of the mouth. The salts and acids of the saliva 
combine with the food, and form tartar, which covers parts 
of the teeth with a hard crust. This can be easily prevented 
by washing the teeth frequently, and completely removing 
all the food and other gatherings of the mouth, after each 
meal, and also in the morning, after an interval of sleep. 

14. The teeth have blood-vessels and nerves; they are 
endowed with life; and, as most people have occasion to 
know, they also have an exquisite sensibility. When they 
are sound, they seem to have little or no sensation; but when 
they are decayed, and exposed to extremes of temperature, to 
very hot or very cold matters, or even to the air, they suffer 
acute pain. 


CHAPTER II. 

Salivary Glands. — Flow of Saliva. •—Mastication necessary. — Ef¬ 
fect of imperfect Mastication. — Pharynx. — (Esophagus. Fpi 
glottis. — Swallowing. 

15. The teeth can only grind the food to powder. In 
this condition, it can neither be swallowed, nor is it fit for the 



14 


PRACTICAL PHYSIOLOGY. 


next stage of the process of digest’on in the stomach. It 
must be not only crushed and divided, but it must be mois¬ 
tened and reduced to a pulpy consistence. For the purpose 
of supplying the necessary moisture, there is provided in the 
mouth a set of glands , which prepare and throw out the 
saliva or spittle, sufficient, in time of health, to moisten and 
soften all the food. These little glands are placed in the 


Fig. II. Salivary Glands. 



cheeks, (Fig. II. «,) and under the tongue, (Fig. II. b ,) and 
under the jaws, (Fig. II. c,) and open, through very minute 
tubes and apertures, into the mouth, (Fig. II. d^d.) When the 
cheeks and tongue are still, these glands are inactive, and 
throw out no more liquid than enough to keep the mouth moist. 
The presence of any matter in the mouth, the chewing of our 
food, tobacco, &/C., and any motion of the jaws, cheeks, or 
tongue, excite these glands, and induce the flow of their 
fluids. All these motions are entirely needless, except when 
we are eating or talking. They are under our control, and 
consequently the flow of saliva is under our command. If, 
then, we use the mouth only for its intended purposes of 
eating and conversation, it will be always moist, but never 
full of saliva; and then we should have no occasion to in¬ 
dulge in the unnatural and offensive habit of spitting. 


DIGESTION AND FOOD. 


15 


16. The saliva flows, during the process of mastication, in 
some measure proportionate to the dryness of the food. The 
salivary glands have a very active sympathy with the appe¬ 
tite, and will sometimes send forth a flow of saliva at the 
mere presence of savory food, so that the common saying, 
that “ one’s mouth waters” at the sight of agreeable dishes, 
is physiologically true. These glands are important assist¬ 
ants in the masticating process, when they and the body are 
in health ; but in fevers, and in some other diseases, these 
organs refuse to act, and the mouth then is dry and parched. 

17. By the united operation of the teeth and the salivary 
glands, the food is first ground into small particles, and then 
made into a soft pulp, in the mouth. Both these operations 
are necessary, for we cannot swallow the morsels unless they 
are divided and moistened, either naturally or artificially. 
Let any one attempt to swallow a mouthful of dry bread 
without chewing, or powdered cracker, without saliva or 
other fluid to soften it, and he will find, that this process, 
w’hich, when proper preparation is made for it, is one of the 
easiest and most agreeable, is now one of the most difficult 
and unpleasant. If the food be not divided while in the 
mouth, it cannot be done afterwards; there is no machinery 
nor power in the stomach to effect this division. 

18. In the back part of the mouth is a second chamber 
called the pharynx , separated from the anterior or front 
chamber by a movable curtain, called the palate. This 
curtain, hanging between these two chambers, is easily 
seen when the mouth is partly opened, and seems then to be 
the farthest boundary of the cavity. But when the mouth is 
stretched widely open, this curtain is raised, and the other 
chamber is disclosed behind it. A little knob or tongue of 
flesh hangs down from the middle of the palate, nearly, and 
sometimes quite, to the tongue, and partially or entirely 
divides the passage-way from the front to the back chamber. 
This gives the appearance of two passages, one on the right 
and the other on the left side. 

19. Four passages open out from the back chamber; one 


16 


PRACTICAL PHYSIOLOGY. 


leads forward to the mouth, the second upward and forward 
to the nose, the third downward to the windpipe and lungs, 
and the fourth downward and backward to the stomach. 
The oesophagus , or gullet , that carries the food and drink to 
the stomach, opens from the farthest part of the mouth, and 
lies behind the windpipe, next to the back-bone. 

20. The windpipe opens between the tongue and the gullet, 
in the front part of the throat. It is seen and felt in all per¬ 
sons, and in some it is very prominent. As the windpipe 
lies between the tongue and the gullet, the food, going from 
the mouth to the stomach, must pass over it, and would be 
liable to fall in if there were not an effectual protection pro¬ 
vided against this accident. The windpipe is made of a 
number of stiff cartilages, and its mouth is always open; 
but there is placed over this mouth a little clapper, or valve, 
called the epiglottis, which is fixed by a hinge to the front 
edge toward the tongue, and opens toward the oesophagus 
behind. 

21. This valve usually stands open to allow the passage of 
air into and out of the lungs. But it is exquisitely sensitive; 
when it is touched with any other matter, it falls down at 
once, and covers the aperture of the windpipe, and protects 
it from any intrusion. Whenever we swallow food or drink, 
the instant the morsel or the fluid reaches this valve, it falls, 
and allows it to glide over it, into the gullet behind, and then 
it rises again to give passage to the air. 

22. While we are swallowing we cannot breathe; if we 
attempt to do this, or to speak, or do any thing which will 
cause this valve to open, some minute particle of food or 
drop of fluid may get into the windpipe, and cause painful 
irritation and coughing. This is a common accident, and 
may be easily prevented by not speaking while attempting to 
swallow food or drink. At the same time that the epiglottis 
falls to allow the food to pass safely over the windpipe, the 
soft palate, the curtain that hangs between the front and the 
back chamber of the mouth, is turned backward and up¬ 
ward, and covers the passage-way that leads to the nostrils, 
and defends them from the ingress of the food. 


DIGESTION AND FOOD. 


17 


23. The upper part of the oesophagus is the 
pharynx. It spreads out like a tunnel in the 
back part of the mouth, and is open to re¬ 
ceive the food from the tongue. The whole 
tube is covered with two sets of muscular 
fibres : one (Fig. III. a, a) running length¬ 
wise from the mouth to the stomach, and the 
other (Fig. III. h) winding around it suc¬ 
cessively from the top to the bottom. These 
muscles have a power of contraction, or of 
drawing themselves up, like the earth-worm, 
and again of relaxing themselves, and being 
stretched out loosely. They draw around 
the gullet like the string of a work-bag, and a ’ _f* Musculo 
thus, narrowing the passage, force onward lengthwise 
whatever food or other matter there is with- b, Circular fibres, 
in it. 

24. When the food is thrown from the tongue into the 
back chamber, and received into the pharynx , or the upper 
portion of the oesophagus, then the uppermost band of muscu¬ 
lar fibres contracts, draws up, and closes this upper end, and 
prevents a return of the food backwards. Then the next 
band contracts, and forces the food onward. Then the third 
band does the same. Thus, while each one is successively 
pressing upon the contents of the tube, these are forced on¬ 
ward and downward to the stomach. While one band is 
contracting, that which is next below it relaxes, to admit the 
entrance of the food. This is the process of swallowing, 
and is performed by the successive action of these circular 
muscles. These bands are so well adapted to each other, 
and work in such harmony, that we are not aware of the 
steps of this operation. Vomiting is performed upon the same 
principle, except that the order of contraction is reversed ; the 
lower fibres first contract, and then those next above, and 
thus their action forces solid and fluid matters upwards, from 
the stomach to the mouth. 


Fig. Ilf. 

Section of the 
(Esophagus. 







18 


PRACTICAL PHYSIOLOGY. 


CHAPTER III. 

Stomach.— Gastric Juice.— Processes of Digestion seen by Dr. 

a. (Esophagus, 
opening into the 
stomach. 

b. Pyloric ori¬ 
fice, opening into 
the alimentary ca¬ 
nal. 

c . c. Duodenum, 
or upper part of 
the alimentary ca¬ 
nal. 

d. Left end or 
great pouch. 

25. The stomach (Fig.IV.) is along, round, and somewhat 
irregularly-shaped sack. It is placed on the left side of the 
abdomen, just below and within the lower ribs, and runs 
crosswise towards the right side, (Fig. V. f.) It has two 
apertures, one towards the left extremity, (Fig. IV.«,) where 
the gullet terminates, and the other on the right extremity, 
(Fig. IV. 5,) where the stomach opens into the alimentary 
canal, (Fig. IV. c, c.) This organ is very expansive, and varies 
greatly in size, according to the quantity of matter contained 
in it. It is sometimes so much distended with a large meal, 
or with liquid or gas, as to hold two quarts or more; at 
other times it is so contracted as to contain less than a pint. 
It usually contracts down to its contents, however small; 
and is therefore always full, either of solid or fluid matters 
or of gas. 


Beaumont. 
Fig. IV. Stomach. 




DIGESTION AND FOOD. 


19 


Fig. V. Relative Position of the Organs of Digestion and 
Respiration. 

a. Right lung. 

b. Left lung. 

c. Heart. 

d. Diaphragm. 

e. Liver. 

f. Stomach. 

g. Front wall of 
the abdomen. 

h. Windpipe. 


26. The average size of the stomach differs with the 
habits of men and the kind of food which they consume. 
It is larger in those who live on vegetable food, which con¬ 
tains less nutriment in the same bulk, than in those who live 
on animal food, which is richer and more nutritious, and 
therefore occupies less space. This difference is more 
marked between the size of the stomach of the carnivorous, 
or flesh-eating animals, and that of the herbivorous, or vege¬ 
table-eating animals. The hare has a much larger stomach 
than the greyhound. The stomach of the cow is large, and 
her alimentary canal is twenty-four times the length of her 
body; whereas, in some of the carnivorous animals, this 
canal is not much longer than their bodies are. Men who 
are in the habit of gormandizing have very great stomachs, 



20 


PRACTICAL PHYSIOLOGY. 


and these are daily stretched to such an extent as would be 
very painful, and even injurious, to more temperate eaters. 

Fig. VI. Inside and Coats of the Stomach. 


a y Mucous coat. 

b , Its edge. 

c, Edge of the mus¬ 
cular coat. 

d, Peritoneal coat. 

e, (Esophagus. 

f, Its opening. 

g, Pyloric orifice. 

h , Right end. 
iy Left end. 



27. The texture of the stomach is fleshy, and very soft and 
flexible. Its thickness varies according to the quantity of its 
contents. It is thinner when it is expanded and its sides are 
stretched than when it is contracted and its sides are 
shrunken. It is composed of three coats , or layers. The 
outer or peritoneal coat (Fig. VI. d) is a part of that covering, 
which wraps about all the contents of the abdomen, and 
forms the outer coat of the whole alimentary canal, and lines 
the walls of this cavity. It is very tough and strong, and 
being attached to the back-bone and the sides of the abdo¬ 
men, it holds with sufficient firmness all the inner organs, 
which it covers, and sustains them in their places; and yet 
it is attached in such a manner as to allow the expansions 
and motions of the stomach and of the canal. 

28. The middle is the muscular coat , (Fig. VI. c;) it has two 
layers of fleshy fibres, or strings, which run crosswise of each 
other at right angles. One of these layers runs lengthwise 
from one end of the stomach to the other. The other layer 
surrounds the sack; and winding in successive circles from 
end to end of the organ, it covers the whole as a similar layer 
of fibres covers the gullet. This muscular coat has a con- 


DIGESTION AND FOOD. 


21 


tractile power, and when it draws itself down, it diminishes 
the capacity of the stomach so as to press upon its contents, 
however small they may be; and again, it expands so as to 
allow the sack to be enlarged for the reception of whatever 
food or liquid is then thrown into it. 

29. The inner or mucous coat (Fig. VI. a) covers the inner 
surface of the organ. It is loose, soft, spongy, and porous. 
It is not elastic, and does not stretch and contract, when the 
stomach is enlarged or diminished. But when the organ is 
distended, this membrane is smooth; and when contracted, it 
is drawn into folds, like the skin of the palm of the hand, 
or of the inner side of the joints of the fingers when closed, 
or of the outside when open. 

30. The anatomy of these three coats is somewhat familiar 
to most people who have eaten tripe, which is a preparation 
of the stomach of the ox or cow. The outer layer of this 
is a dense, tough covering of fatty matter, and comparatively 
strong. The next or middle layer is composed of reddish 
fibres. These are stringy, and are what is commonly called 
the lean meat. This layer differs in thickness in different 
parts of the stomach. The inner layer is a thick, soft, fatty 
matter, and filled with superficial cells. The human stom¬ 
ach has similar coats, which are arranged in the same man¬ 
ner, and perform the same duties. 

31. These three coats, or coverings, constitute the stomach. 
They have each a distinct part to perform in the digestive 
process, and each one is fitted for its peculiar work, and for no 
other. The outer coat gives strength and support to the 
whole. The middle coat expands and contracts, to give due 
size to the sack; it produces the motions in the stomach, 
which agitate the food and promote the work of digestion ; 
and finally this coat presses the sack down upon the contents, 
to expel them when they shall be digested. The inner or 
lining coat exudes upon its own surface a slimy, mucous 
substance, which protects it from the irritation of the mat¬ 
ters that are put into the organ, and also prepares th‘; gastric 
juice — a powerful fluid which dissolves the food. 


22 


PRACTICAL PHYSIOLOGY. 


32. The gastric juice is prepared within the walls of the 
stomach, and thrown out from its mucous or lining mem¬ 
brane in a manner similar to that in which the saliva is 
thrown out from the glands of the mouth, or the sweat is 
poured out from the skin. This fluid has singular and re¬ 
markable qualities; it is peculiar to the stomach, for noth¬ 
ing like it is found any where else, within or without the 
animal body. It is prepared for the purpose of dissolving 
the food and converting it into the nutriment of the blood. 

33. This is a very powerful fluid. It dissolves the proper 
and natural sorts of food — meat, bread, vegetables, fruits, 
mixed in every variety of combination, and cooked in all 
kinds of ways. The healthy stomach, when properly fed, 
converts all these into a pulpy mass, which is to supply the 
waste of the blood, and then nourish the whole body. This 
fluid differs in different animals, according to the nature of 
their food. Thus the lion, which lives upon flesh, has a 
gastric juice somewhat different, in its qualities and powers, 
from that of the ox, which lives upon grass and grains. In 
man, whose food is composed of both flesh and grain, it dif¬ 
fers somewhat from either, but partakes, in some degree, of 
the qualities of both. 

34. It has been ever easy to learn the structure of the 
stomach, and the arrangement of its coats, and its relation 
to other organs. But the method by which these operate, 
and the processes of digestion, have been left to inference or 
conjecture, until within a few years. Men could watch their 
own sensations of comfort or pain, and notice the results 
of strengthening and weakness from eating; but they could 
not see the steps, and had no means of knowing, for a cer¬ 
tainty, what was going on in the stomach, until an opportu¬ 
nity was offered to Dr. Beaumont, of the United States army, 
in the year 1S22, and afterwards. A young soldier, Alexis St. 
Martin, received a gun-shot wound in his left side, which laid 
his stomach open. The aperture did not close up, but left an 
opening, through which food could be put in and taken out, 
and the whole process ef digestion observed. A flap of skin 


DIGESTION AND FOOD. 


23 


and flesh hung over this unnatural passage-way, and closed 
it, and retained the contents of the stomach. But it could 
be raised at any time, and the cavity of the stomach exposed. 

35. Dr. Beaumont took St. Martin into his family, and 
tried a great variety of experiments upon him, and made re¬ 
peated observations in regard to his digestion, during the year 
1825, and from 1829 to 1833. Dr. B. had thus an opportu¬ 
nity, which has been afforded to no other man on record, 
of watching the processes of digestion, and observing every 
step as it occurred. St. Martin masticated his food in his 
mouth, and swallowed it in the usual way. But it could 
be examined or taken out through the aperture, at any stage 
of digestion in the stomach. Food or fluids could be put 
into the stomach, gastric juice could be taken out, a ther¬ 
mometer passed in, and the temperature ascertained. 

35. St. Martin took the various kinds of food usually 
eaten. These were prepared in all the common methods 
of cookery. Dr. B. closely watched them after they were 
eaten, and noticed the changes as they successively took 
place in each of the different articles which had been taken. 
He watched the effect of every kind of food upon the 
stomach, the flow of the gastric juice, the action of this fluid 
upon the matters presented to it, and the movements of the 
sack. He observed, also, precisely the time required to 
digest or to change each article into chyme. He kept a 
minute record of all these facts, and has since published the 
results of his observations to the world. To this interesting 
volume I am indebted for many of the facts stated in this 
book. 


24 


PRACTICAL PHYSIOLOGY. 


CHAPTER IV. 

Gastric Juice secreted in the Stomach when Food is swallowed.— 
This Quantity of Juice is the Measure of the Food to be eaten. — 
Hunger. — Gastric Juice combines with Food when swallowed, 
if eaten slowly. 

37. But even Dr. Beaumont’s observations do not explain 
the mysteries of digestive power and action. He could only 
discover the steps by which nature accomplishes this won¬ 
derful transformation of dead food into the nutriment of the 
living blood. The food is masticated and swallowed. It 
then is carried to the left or larger end of the stomach, and 
there lodged in a great pouch. As soon as the food is 
swallowed, some gastric juice, sufficient to moisten it, is 
poured out from the lining membrane, and mingles with and 
softens it. The more completely the food has been masti¬ 
cated, and the more minutely jKhas been divided in the 
mouth, the more readily does this gastric juice enter into 
and combine with it. First it mixes only with the surface 
of each broken portion, and, as fast as the minute particles 
are softened by this fluid, they are separated by the continual 
motion of the stomach, and then the fluid has opportunity to 
mingle with other particles; and, these being removed, still 
other particles are exposed and moistened; and thus the 
work goes on, until all the food is wet and softened by this 
dissolving fluid. 

38. The stomach is not always full of gastric juice. 
Usually there is none of this fluid in it, except when some 
food or other matter is there to excite the lining membrane 
to secrete it and pour it out. When we put a morsel into 
the mouth and begin to move the jaws, the salivary glands 
are stimulated to pour out saliva sufficient to moisten it. In a 
somewhat similar manner, the same morsel, when it reaches 


digestion and food. 


25 


4he stomach, stimulates the mucous coat to throw out suf¬ 
ficient gastric juice to dissolve it. In neither case is fluid 
enough given out at once to mix with an entire meal. But 
as we see it in the mouth, so in the stomach it is given out, 
part by part, as often as a portion of food arrives and de¬ 
mands it. Even this small quantity is not poured out with a 
gush, but it oozes out slowly, as the perspiration oozes from 
the forehead, until there be enough to mix with the new 
morsel that is swallowed. This is not a rapid process; it 
takes a few moments to wet each morsel. If, then, we swal¬ 
low more rapidly than the morsels can be wet with the juice, 
they must accumulate, and wait for the fluid to come. 

39. This secretion and flow of gastric juice commences 
as soon as any food reaches the stomach, and then continues 
to flow, if stimulation by new morsels is successively repeat¬ 
ed. But this secretion is not without end. This liquid 
cannot, like the saliva in the mouth, be made to flow as long 
as we wish. There is a limit to the gastric juice which will 
be secreted at any one time. Dr. Beaumont says, “ When 
the alimentary matter is received into the stomach, this fluid 
then begins to exude from its proper vessels, and increases 
in proportion to the quantity of aliment naturally required 
and received.” * It flows, then, not in proportion to the food 
which we may happen to eat, but in proportion to the quan¬ 
tity of nutriment which the body needs. When, therefore, 
so much of this juice is poured out as will dissolve what food 
we need at any one time, it will stop, and the mucous mem¬ 
brane will give no more. And, as only a definite proportion 
of aliment can be digested in a given quantity of this fluid, 
if more be eaten than this quantity can dissolve, — that is, if 
more food be swallowed than the body needs to supply its 
waste, — the excess either remains in the stomach undigested, 
and is there a cause of intense pain and oppression, or it is 
thrown out and onward, in a crude state, to disturb the 
organs beyond. 


3 


* Observations, p. 85, 


20 


PRACTICAL PHYSIOLOGY. 


40. Knowing, then, that the stomach can give out only 
a limited quantity of gastric juice at any one time, and that 
this fluid can dissolve only a limited quantity of food, and 
also that this corresponds with the wants of nutriment in the 
body, we have a measure of the amount of food which should 
he taken at each meal; that is, as much as the gastric juice 
can combine with in the stomach and digest. This, at first 
sight, would seem to be unknown, and therefore no guide for 
us. But it can be ascertained by watching the effects of 
eating. There is an apparent understanding between the 
general system and the stomach; at least, there is such a 
sympathy between them that, when the one wants nourishment, 
the other is ready to digest it. This gives the sensation of 
hunger, which appears to be in the stomach. When this is 
felt, the lining membrane is ready to give forth the gastric 
juice to digest the food; and, as long as the hungry feeling 
continues, this fluid may flow. But when this ceases, there 
is no more need of food, no more sensation of want, and no 
more digestive power than sufficient to dissolve what has 
been already eaten. Then there is a feeling of satisfaction 
and ease in the stomach, for the appetite and craving are 
gone. 

41. We can make use of this guide to the proper quantity 
of food, and measure it by the quantity of gastric juice which 
can be supplied at one time, only when we eat slowly, when 
the morsels which we swallow, and the fluid which is to dis¬ 
solve them, keep pace with each other, and meet together in 
the stomach. By this cautious proceeding, we adapt the 
supply of food exactly to the wants of the body, and stop as 
soon as this want ceases. But if we eat mor 3 rapidly than 
this, and continue to eat at this rate as long as the gastric 
juice continues to be secreted, the food gathers in the 
stomach faster than the digesting fluid. There is an accumu¬ 
lation of this waiting to be moistened. And when, finally, as 
much of this liquid is given out as can be afforded, there is 
still this excess of food already in the stomach, so much more 
than is needed or can be digested. 

C 


DIGESTION AND FOOD. 


27 


42. Hunger is the sensation of want of more nutriment 
in the body. But this is felt, not in the body where nutri¬ 
ment is needed, but in the stomach, and there only when that 
organ is ready to give out sufficient and proper gastric juice 
to digest the food which is required. There must be a cor¬ 
respondence between the general frame and the stomach, to 
produce this feeling of hunger. The one must be in need of 
more nutriment, and the other ready and able to digest it. 
It is not enough that the body is in want. If the stomach 
cannot render aid in the supply, there is no hunger. In fever, 
the body wastes away and wants nourishment; but the 
stomach cannot digest, and consequently asks for no food. 
When nutriment is wanted, the body speaks to the stomach, 
and the stomach, if it have power of digestion, speaks to the 
nervous system. This is hunger. This sensation is felt in 
the stomach, and there it continues until all the gastric juice 
which will dissolve the needed quantity of food is poured 
out and combined with it, and then it ceases for the time. 

43. Since writing the last section, I have been consulted 
by a man, who complained that he had a very great appetite, 
but a very weak and painful digestion. He said that he sat 
down to his dinner voraciously hungry, and ate very rapidly, 
without giving his mouth time to masticate his food. He ate 
much more than his companions, and yet he rose from his 
table hungry and went immediately to his work, from which 
he was absent a shorter time than his fellows, who ate less 
than he did. His hunger continued about twenty minutes or 
half an hour after he left his table, and then left him in pain. 
His food oppressed him; it lay like a weight in his stomach 
for several hours; and he was scarcely relieved of the distress 
before the time for another meal came round. 

44. The explanation is this: Mr. D. is a man of active 
habits, and his frame therefore wants nutriment. His stomach 
can digest and is ready to give out gastric juice sufficient to 
dissolve as much food as is needed, and he is consequently 
hungry. To gratify his keen appetite, and to save time at 
his meals, he has acquired the unnatural habit of eating 


28 


PRACTICAL PHYSIOLGY. 


rapidly. He swallows his food faster than the gastric juice 
is prepared to mix with it. Before enough of this fluid is 
poured out for the first morsel, the second is swallowed, and 
before this is moistened, a third arrives; and thus every 
moment increases this mass of food waiting in the stomach 
for its dissolving fluid. As long as this juice continues to 
flow, there is an appetite. But befoie it ceases, he has eaten 
so much that his tardy reflections tell him that he has eaten 
enough, and more than enough. Obedient to his reflections 
rather than to his sensations, he rises from his table before he 
has satisfied his appetite, which continues for several minutes 
longer, until the gastric juice ceases flowing and mixing 
with the food. When this happens, there is yet in the 
stomach some food unmixed with the fluid, and this is so 
much more than can be dissolved. The stomach struggles 
painfully for several hours to digest or get rid of this excess, 
and hence comes the oppression that hangs heavily upon him 
through the interval between his meals. 

45. The work of digestion commences immediately after 
we begin to eat; as soon as we swallow one morsel, some 
gastric juice is given out and combines with it. The second 
morsel excites the flow of more of this fluid, and enough for 
its own solution. In the same manner, each successive 
morsel provokes the secretion of as much of this fluid as it 
needs, until all shall be given out that can be given at 
that time. If, therefore, we eat slow’y and naturally, by the 
time that we shall have finished eating, all the food will be 
moistened. In a few minutes more, all the gastric juice that 
can be prepared on that occasion is thrown into the stomach; 
and this is sufficient, in health, to dissolve as much food as 
the nutrition of the system then needs, and no more. 


DIGESTION AND FOOD. 


29 


CHAPTER V. 

Motions of the Stomach. — Digested Food homogeneous. — Heat of 
Stomach during Digestion. — Cold interrupts Digestion. — Pyloric 
Valve. 

46. This mixture of the fluid with the food in the stomach 
is aided by the action of its muscular coat, and of the 
muscles of respiration. The muscular coat habitually re¬ 
duces the size of the sack down to its contents. When 
more food or drink is received, it relaxes, and allows the sack 
to expand and give the new matter room. But this coat is 
uneasy. It not only relaxes, but it again contracts, and 
presses upon the food; and then again it loosens. This is 
repeated gently and continually; and by this means the 
food is kept in slight motion, as long as the process of diges¬ 
tion is going on. These movements are assisted by the 
muscles of respiration. The stomach lies in the upper part 
of the abdomen, (Fig. V. f y ) and just below the chest, where 
the lungs are situated. Immediately above, and in contact 
with it, the diaphragm (Fig. Y. d, d ) stretches across the 
body from side to side, and from the back-bone to the breast¬ 
bone. 

47. This great muscle is the partition wall between the 
chest and the abdomen, and moves with every breath. 
Every time we draw our breath, this presses downwards 
upon the stomach, enlarges the cavity of the chest, and gives 
room for the air to flow into the lungs. Then, when we 
exhale, the abdominal muscles — those which principally con¬ 
stitute the front wall of the abdomen — contract, press upon 
the stomach, and throw it upon the diaphragm, and force the 
air outward. Thus the stomach is kept in incessant motion. 
Every inspiration of air presses it downward and outward, 
and every expiration presses it upward and inward. These 
combined movements keep the food in such agitation, that it 
becomes thoroughly mixed with the gastric juice, and the 

3* 


30 


PRACTICAL PHYSIOLOGY. 


digestive process is by this means very materially hast¬ 
ened. 

48. The food is first mixed with and then dissolved in the 
gastric juice. Then all the peculiarities of the articles which 
we have eaten are lost. No trace of the original form of the 
digestible and digested matter can be found. Meat, bread, 
fruits — all are reduced to one homogeneous pulp. Whatever 
we may have eaten, the pulp, so far as we can discover, is 
the same. When we examine the digested food in the 
stomach of the man whose diet is mostly meat, in that of 
another whose diet is exclusively bread, and in that of the 
child, whose whole nutriment is milk, the eye and the 
fingers perceive no difference; and, when they are chem¬ 
ically analyzed, they are found to be very nearly alike. This 
new pulp is called the chyme, and is now ready to go onward 
from the stomach to the alimentary canal. 

49. This process of digestion requires the natural heat of 
the animal body. Dr. Beaumont passed the thermometer 
frequently into St. Martin’s stomach, and found that its tem¬ 
perature was 100°, which is two degrees higher than the 
natural temperature of the body. He also found that cold 
retarded the process of digestion. He threw into the stom¬ 
ach a single gill of water at the temperature of 50°, which 
reduced the temperature of the whole contents of the stom¬ 
ach 30°, that is, down to 70°. Digestion was then sus¬ 
pended, until the temperature was elevated to its natural 
standard. 

50. Dr. Beaumont took a quantity of the gastric juice 
from St. Martin, and divided it into two portions. He put 
some pieces of meat into one portion of this, cooled down to 
34°, and some into another portion, warmed to 100°, the 
natural temperature of the stomach during digestion. These 
were kept at these temperatures for many hours. At the 
same time St. Martin swallowed meat of the same kind. In 
one hour the meat in the stomach was partially digested; 
that in the warm gastric juice out of the stomach was nearly 
in the same condition, while that in the cold gastric juice 


DIGESTION AND FOOD. 


31 


was much less advanced. When the meat was entirely di¬ 
gested in the warm fluid, it was very little changed in the 
cold fluid. At the end of twenty-four hours the last was no 
more digested. But then he warmed this fluid to 100°, and 
kept it at that temperature, and digestion commenced and 
advanced regularly, as in the other parcels. 

51. In his other experiments, Dr. Beaumont found that 
cold gastric juice acted not at all, or very imperfectly. 
Hence he concluded that heat to a certain degree is neces¬ 
sary, to give it the power of dissolving food. Dr. Carpenter 
thence infers that the practice of eating ice after dinner, or 
even drinking cold fluids or ice-water during dinner, or at 
any time of eating, is very prejudicial to digestion. If this 
be true, then all drinks which are colder than the stomach 
must interfere with the action of the gastric juice to an ex¬ 
tent in proportion to their coldness. For, if a temperature of 
100° is necessary for digestion, then any thing, whether food 
or drink, that cools the gastric juice below this degree, must 
suspend the digestive process until the heat of the body, or 
living power of the stomach, shall warm the fluid up to the 
necessary temperature. 

52. The stomach (Fig. IV.) is large, and has its principal 
cavity at the left end, where the' food is received through the 
oesophagus from the mouth. It grows smaller towards the 
opposite end, and finally opens, by a small aperture at its right 
extremity, into the alimentary canal. At this point of junc¬ 
tion, it is surrounded by a strong circular band of muscular 
fibres, which, by contraction, can completely close the open¬ 
ing, as a string closes the mouth of a bag, and prevent the 
passage of any thing through. This is the pyloric valve , 
(Fig. IV. b,) which acts as a faithful sentinel, and retains 
the contents of the stomach during the process of digestion. 
While the food is undergoing the operation of churning and 
mingling with the gastric juice, it binds itself closely around 
the passage-way. The motions of the stomach, and the 
pressure of the respiratory muscles, w’ould very naturally 
force the food out of this sack, if it were not thus effectually 
secured. 


32 


PRACTICAL PHYSIOLOGY. 


53. This ever-watchful door-keeper has a special duty to 
perform. Its business is to retain the food in the stomach 
until it be digested, and then to let it pass onward. For this 
purpose, it seems to be endowed with a kind of intelligence, 
by which it discriminates between the crude and the dis¬ 
solved matters that present themselves to it, and with a sort 
of discretionary power, by which it opens and lets the finish¬ 
ed chyme pass out, but closes and prevents the passage of 
that which is not so reduced to a pulp. While the stomach 
is empty, it may be relaxed, and the doorway left open; but 
as soon as any food is swallowed, it shuts the door, and holds 
it tight until this food be digested. As fast as any portion 
of the food is turned into chyme, it is carried by the motions 
of the stomach to the right end; then the valve relaxes, the 
door opens, and the digested food passes out. But, with a 
quick perception of the differences of condition of the food, 
it closes the moment the digested portion has gone out, and 
the undigested portions offer themselves. 

54. We sometimes eat food of a kind which the stomach 
cannot digest. We sometimes eat more at a meal than the 
gastric juice can dissolve. In these cases, the stomach di¬ 
gests what it can, and makes great effort to digest the rest. 
When it becomes wearied with its unsuccessful efforts, it en* 
deavors to relieve itself of the indigestible portion by thrust¬ 
ing it through the aperture at the right end into the aliment¬ 
ary canal. But as this crude matter is neither digested nor 
prepared for the action of the next organ, the valve refuses 
to open and let it go through. Again this is sent back, and 
again the stomach makes its fruitless attempts to digest it; 
and thus failing a third and a fourth time, presents it to this 
doorway for passage. This is refused over and over; the 
vaive closes with a greater and even more painful force; 
until, at last, fatigued with the resistance, it yields to the im¬ 
portunity of the stomach, and permits the undigested and 
indigestible matter to go through. While this struggle is 
going on, we feel a distressing oppression about the right 
side, just below the short ribs. This usually happens about 


DIGESTION AND FOOD. 


33 


two or three hours after eating, and is caused by the ineffect¬ 
ual effort of the stomach to convert the indigestible food into 
pulpy chyme, and the resistance of the valve to its passage 
outward. 

55. But after a painful struggle of the stomach to get rid 
of that which it cannot master, and of the valve to hold back 
that which ought not to pass, the food is at length forced into 
the alimentary canal. There it is a strange matter; it is 
no more suited for this organ than it was for the stomach. 
These organs were made to receive, the one masticated and 
digestible food, and the other the chyme, or the food digested 
and reduced to a fine pulp. All other matters are foreign to 
them, and create disturbance and cause pain. The natuv 
ral and healthy work of the stomach is preparatory to the 
work of the alimentary canal; and, unless the first organ has 
done its proper work upon the food before it enters the sec¬ 
ond, the last can do little, and generally it can do nothing 
with it. It has no more power over food that is not digested, 
than the other had over food that could not be digested. As 
long as it remains, then, in the body, it irritates the sack 
which contains it, and gives distress to the whole system. 


CHAPTER VI. 

Time required for Digestion. 

56. Digestion commences in the stomach as soon as the 
food is swallowed, and continues from one to five hours — 
varying according to the kind of food, and the health of the 
person. Dr. Beaumont found that the various articles of diet 
differed very much as to the time required for their solution 
in the stomach. Pigs’ feet and tripe soused were changed 
to chyme in one hour, while roasted fresh pork was not dis* 
solved in less than five hours and a quarter. Other articles 
required various periods, ranging between these extremes. 
Tiie average and usual time required for the complete diges 



34 


PRACTICAL PHYSIOLOGY 


tion and transmission of ordinary meals from the stomach is 
three hours and a half. Persons differ very much, according 
to their health and their habits. Those who have not abused 
their digestive organs — who have not overloaded them, nor 
tasked them with indigestible matter — have much more active 
stomachs than those who have misused these organs. The 
active and the energetic digest more vigorously than the 
sluggish and the inert. The following table, showing the 
time required for the digestion of various articles of food, is 
taken from Dr. Beaumont’s work, p. 269. 

57. Mean Time required for the Digestion of various 
Articles of Food in the Stomach. 


Articles. 


Apples, sour, hard,. 

-, mellow, 

~-, sweet, do., . 

Aponeurosis,* . . . 
Bass, striped, fresh, 

Barley,. 

Beans, pod,. 

Beef,fresh, lean, rare, 

-, dry, 

-steak,. 

-, with salt only, 

-, with mustard, 

-, fresh, lean,. . 

-, old, hard, ) 

salted,.5 

Beets,. 

Brains,. 

Bread, wheat, fresh, 

-, corn, .... 

Butter,. 

Cabbage head, . . . 
-, with vin- ) 


Cake, sponge, . 
Carrot, orange, 


Cartilage,* 


Catfish, 

Cheese, old, strong, 
Chicken, full-grown, 
Cod B h, cured, dry, 


Prepara¬ 

tion. 


Raw. 

Raw, 

Raw, 

Boiled, 

Broiled, 

Boiled, 

Boiled, 

Roasted 

Roasted, 

Broiled, 

Boiled, 

Boiled, 

Fried, 

Boiled, 

Boiled, 

Boiled, 

Baked, 

Baked, 

Melted, 

Raw, 

Raw, 

Boiled, 

Baked, 

Boiled, 

Boiled, 

Fried, 

Raw, 

Fri cas’d 
Boiled, 


Time. 


50 


30 


Articles. 


Corn, green, and ) 

beans, . ) 

- bread, .... 

cake, . 


Custard / 

Dumpling, apple, 
Ducks, domesticated, 
-, wild, 


Prepara¬ 

tion. 


Eggs, fresh, 


-■••4 


-, w'hip’d, 


Flounder, fresh, 
Fowl, domestic, 


Gelatine,. 

Goose,. 

Heart,. 

Lamb, fresh, .... 
Liver, beefs, fresh, 
Meat hashed with ) 
vegetables,. . . 5 
Milk,. 


Mutton, fresh, 


Boiled, 

Baked, 

Baked, 

Baked, 

Boiled, 

Roasted 

Roasted 

Boiled 

hard, 

Boiled 

soft, 

Fried, 

Roasted, 

Raw, 

Raw, 

Fried, 

Boiled, 

Roasted, 

Boiled, 

Roasted, 

Fried, 

Broiled, 

Broiled, 

Warm’d, 

Boiled, 

Raw', 

Roasted, 

Broiled, 

Boiled, 


Time. 


45 

15 

45 

30 

30 

30 

15 

30 

30 

30 

30 

30 

30 

15 

15 






















































DIGESTION AND FOOD. 


35 


Articles. 

Prepara¬ 

tion. 

Oysters, fresh, . . . 

> * • * 

; • • • 

Raw, 

Roasted 

Stewed, 

Parsnips,. 

Boiled, 

Pig, sucking, .... 

Roasted 

Pigs' feet, soused, . 

Boiled, 

Pork, fat and lean,. 

Roasted i 

-, recently salt'd, 

Boiled, 

Fried, 

Broiled, 

Raw, 

; 

; 

9 

y 

Stewed, 

- steak. 

Broiled, 

Potatoes, Irish, . . . 

; • • • 

> • • • 

Boiled, 

Roasted 

Baked, 

Rice, . 

Boiled, 

Sago,. 

Boiled, 

Salmon, salted, . . 

Boiled, 

Sausage, fresh,. . . 

Broiled, 

Soup, barley,.... 

Boiled, 

--, bean 

Boiled, 



Time. 


G 

a 

C 

§ 

Articles. 

2 

55 

Soup, beef, vege- ) 

3 

15 

tables, and bread, $ 

3 

30 

--, chicken, . . . 

2 

30 

-, marrow-bones 

2 

30 

-, mutton, . . . 

1 


-, oyster, .... 

5 

15 

Spinal marrow, an- ) 

4 

30 

imal,.) 

4 

15 

Suet, beef, fresh,. . 

3 

15 

-, mutton,.... 

3 


Tapioca,. 

3 


Tendon,*. 

3 

15 

Tripe, soused, . . . 

3 

30 

Trout,salmon, fresh, 

2 

30 



2 

30 

Turkey, domesti- ) 

1 


cated,.) 

1 

45 


; 

4 


-, wild, . . . 

3 

20 

Turnips, flat, .... 

1 

30 

Veal, fresh, .... 

3 


9 * * * * 



Venison steak, . . . 


Prepara¬ 

tion. 


Boiled, 

Boiled, 

Boiled, 

Boiled, 

Boiled, 

Boiled, 

Boiled, 

Boiled, 

Boiled, 

Boiled, 

Boiled, 

Boiled, 

Fried, 

Roasted, 

Boiled, 

Roasted, 

Boiled, 

Broiled, 

Fried, 

Broiled, 


Time 


e 

a 


I 


4 

3 

4 
3 
3 

2 

5 

1 

2 
5 

1 

1 

1 

2 

2 

2 

3 

4 
4 
1 


15 

30 

30 

40 

30 

30 

30 

30 

30 

30 

25 

18 

30 

30 

35 


* Cartilage is usually called gristle. Aponeurosis and tendon are very strong and 
tough parts of the flesh, somewhat similar to cartilage. 


58. These are the results of many hundreds of observa¬ 
tions upon St. Martin. The time stated in regard to each 
article, is the average time required to digest it. From these 
experiments we see that there is a very great difference in 
the time required for the digestion of the various articles of 
food. Rice and souse are digested in one hour; salmon 
trout and sweet apples, in one hour and a half; beef’s liver, 
codfish, and tapioca, in two hours ; fresh beef and mutton, in 
three hours; veal broiled, and ducks, in four hours. Fresh 
pork, roasted, required five hours and a quarter for digestion. 
St. Martin’s power of digestion may not exactly correspond 
with that of all other men. Some may require a longer, 
some a shorter time to digest these articles of food. Still he 
may be fairly considered as a representative of the average 
of mankind; and probably we, if in good health, shall digest 
these several articles in about the same time that he did. 

















































36 


PRACTICAL PHYSIOLOGY. 


CHAPTER VII. 

Fluids drunk with Food impede Digestion. — Stomach acts more 
easily on a large than on a minute Quantity of Food. — Meat bet¬ 
ter digested if mixed with Vegetables. — Gastric Juice mixes 
easily with light, but not with heavy Bread. — Light Bread soaks 
readily in Water, but heavy Bread does not. 

59. The first work of the stomach in digestion is to get 
rid of all the fluid which has been swallowed with the food. 
In fifty minutes after Martin had dined on vegetables, soup, 
beef, and bread, Dr. Beaumont found that the fluid portion 
had been absorbed and carried away from the stomach, and 
the remainder was of a thicker consistence than usual, after 
a more solid food had been taken. This is necessary, in or¬ 
der that the gastric juice shall not be diluted and weakened, 
and its power of dissolving the food diminished. 

60. Drink taken with food, then, must either reduce the 
power of the gastric juice, or postpone the work of digestion 
until the stomach shall have relieved itself of this needless 
matter, and in either case, suspend the digestive process. 
It is a common notion that those who have weak stomachs 
should take their food in a diluted state. They are advised 
to live upon weak broths, soups, teas, &c., which seem to 
require less effort of digestion. But this is not always good 
advice. These liquids may require more effort, and are, 
therefore, inappropriate food for many of the feeble. 

61. The natural secretions of the mouth afford sufficient 
fluid to aid in the grinding and softening the food, and to 
prepare it for swallowing; and the gastric juice in the stom¬ 
ach is sufficient for its solution there. Upon this principle, 
the taking of tea or coffee, or even cold water, with our 
meals, cannot be of advantage; on the contrary, they must 
be injurious. Dr. Warren says, “The quantity of drink 
required for health and comfort is very small. In cold 
weather, a pint of liquid in twenty-four hours is sufficient; in 
the hot seasons, this quantity may be increased, but this 


DIGESTION AND FOOD. 


37 


mcrease is rarely necessary when a reasonable amount of 
fruit can be obtained.” * 

62. The stomach acts more easily upon a large than on a 
very small quantity of food. As the hands find it easier to 
grasp and hold a cane than a quill or a wire, and the arms can 
more easily clasp an armful of wood than a single stick, 
so the muscular coat of the stomach finds less difficulty in 
grasping and pressing upon a full meal than a little morsel. 
The quantity of nutriment in food is not always in propor¬ 
tion to its bulk; some kinds contain very much, and others 
very little, in the same space or weight. A pound of beef is 
more nutritious than a pound of bread, and a pound of bread 
contains more nutriment than a pound of roots. 

63. Meats are very concentrated; that is, they contain 
great quantities of nutriment in small bulk ; and if we were 
to live upon these alone, we should eat a small quantity — 
smaller than the stomach could manage with the greatest 
ease to itself. This difficulty is obviated by mixing meat 
with bread and vegetables. Some of the rude tribes in the 
extreme northern regions live upon the coarsest and most 
concentrated meats. But they find it better to mix this with 
bread, potatoes, or other roots, with bran, or even sawdust, 
for the purpose of facilitating the action of the stomach. 

64. In order that the food should be mixed the most freely 
with the gastric juice in the stomach, it should be not only 
well divided in the mouth, but it should be of such a nature 
that the gastric juice can get access to all the minute par¬ 
ticles, and separate them from each other. With light bread, 
that is thoroughly baked, and somewhat dried, this is easily 
accomplished. But heavy bread is adhesive, and the parti¬ 
cles cling together and form a solid mass, so compact that it 
would be very difficult for any fluid to penetrate it. 

65. The difference is easily shown, and is probably famil¬ 
iar to all; if not, the experiment can be tried in one moment, 
by throwing a piece of light, porous bread, that has been 
baked twenty-four hours, and is somewhat dried, into water 

* On Preservation of Health, p. 62. 


4 


38 


PRACTICAL PHYSIOLOGY. 


Immediately the water penetrates into all the cells, and fills 
all the pores; the bread absorbs more and more, and swells; 
and soon the mass is much enlarged, and is completely filled 
with water. In fact, it is itself mere pulp. If we divide it, 
we shall find that water has come in contact with every par¬ 
ticle ; every one, however minute, is wet. 

66. Again, throw a piece of heavy, compact bread, that 
has no cells in it, into water, and let it remain as long as the 
other, and then examine it, and it will be found that it is as 
heavy as it was before; the water has not penetrated it — it 
has absorbed none; it is not enlarged, and the inner parti¬ 
cles are not reached by the fluid; they are as dry as they 
were before the piece was thrown into water. The same 
effect takes place in the action of the gastric juice in the 
stomach. It finds it easy to penetrate among and wet the 
particles of the light, and hard to enter the heavy bread. 
This last then remains for a long time a solid, compact mass, 
or a mass of compact portions, which cannot be dissolved; or, 
if it be dissolved, it is not without much difficulty and pain, 
and after a long perseverance of the organ in its almost 
fruitless work. 

67. We can determine this quality of bread even without 
the trouble of throwing it into water. New bread is 
almost always adhesive, and its particles disposed to cling 
together. If we take a piece of this, or of heavy bread, and 
roll it between the fingers, it forms into a compact ball or 
roll, so close that it is plain that it will not readily admit wa¬ 
ter to soak it. But if we try the same with old and light 
bread, it separates and falls into crumbs. It is impossible 
to make it into a ball. This would be easily soaked in 
water, and easily digested in the stomach, which is not the 
case with the new or the heavy bread. 


DIGESTION AND FOOD 


39 


CHAPTER VIII. 

Chyme. — Alimentary Canal. — Mucous Membrane. — Lacteals. — 
Chyme in the Duodenum. — Chyle: differs with difference of 
Food. — Carried to Blood-Vessels. — Three Stages of Digestion. 


68. When the stomach has finished its work, the food is 
converted into chyme. This is a fine pulp. It is of a grayish 
color and sweetish taste, and somewhat insipid. It is thin 
and viscid to the touch. This is the whole mass of food 
changed by and mixed with the fluids of the stomach. It is 
the same in appearance throughout: all the distinctions of 
the various kinds of aliment are lost. We find no trace of 
the bread, meats, or vegetables which have been eaten: all 
are reduced to one homogeneous compound. Having passed 
through all the changes that can be effected in the stomach, 
the pyloric valve opens, and the muscular coat contracts and 
presses it onward into the duodenum , which is the first link 
of the alimentary canal. When indigestible matters are 
eaten, they, after a labor of some hours, are forced into the 
same canal, and there again they are mixed with the digested 
chyme. 

69. The alimentary canal is composed of three coats, 
which are similarly arranged and serve similar purposes to 
those of the stomach. The outer of these coats is strong 
and thick, and gives support to the whole canal; by this coat 
the organ is attached to the back-bone and held in its place. 
The middle coat is like the lean meat of tripe; it is com¬ 
posed of two sets or layers of fibres, one of which winds 
around the tube — the other runs lengthwise from end to 
end. The circular band regulates the size of the tube, by 
keeping it always pressed down upon its contents. When food 
is within this organ, these fibres contract, one after another, 
successively, and, pressing upon the matters contained within, 
force them onward. The longitudinal fibres shorten the 


40 


PRACTICAL PHYSIOLOGY. 


canal or its parts, and by this means they aid in carrying the 
food forward. 

70. The inner lining, called the mucous membrane , differs 
from that of the stomach in so far as it secretes no gastric 
juice, nor any other fluid, except the slimy mucus with 
which the whole inner surface of the canal is moistened and 
protected from any irritating quality of the contents. This 
membrane is loose and flabby, and, when the canal is empty 
and contracted, it is drawn into wrinkles or folds, and seems to 
be too large for the sack. But when the canal is distended 
with food, or any other matter, it is drawn out, and lies more 
smoothly over the inner face of the sack. The surface of this 
/ining is soft, like velvet, and filled with myriads of pores, which 
perform an important part of the work of digestion. Besides 
these folds, which are made in the mucous membrane by the 
contraction of the canal, there are other folds, which run 
around the inner surface of the tube crosswise of its length. 
These are permanent, whether the tube be contracted or 
distended. These afford a larger surface for the absorbent 
pores, and, by projecting into the canal, they retard the prog¬ 
ress of the food in some degree, so as to give the absorb¬ 
ents opportunity to take up the nutritious portion. 

71. These numberless little pores, or tubes, have theii 
open mouths upon the inner surface of the alimentary canal. 
They run from the inner channel outward through the walls 
of this canal. Their mouths are so small as to be invisible, 
even by aid of a powerful microscope; and yet they are so 
numerous as to cover over all the inner surface of this organ. 
Their duty is to absorb or suck up the finer and nutritious 
portion of the digested food, which, when it is in these little 
tubes, has the appearance of milk. These are, therefore, 
called the lacteal absorbents. These tubes, when they first 
start from the inside of the canal, are almost inconceivably 
small, but they unite together, two and two, and more, and 
thus become fewer and larger. The larger tubes again unite 
and form other and still larger ones, until they all are joined 


DIGESTION AND FOOD. 


41 


in one large tube, called the thoracic lacteal duct. This 
goes along the inner side of the back-bone, from the abdo¬ 
men to the upper part of the chest, and opens into the great 
vein, at the right side of the heart. These mouths and 
tubes, small and large, and this duct, constitute what is called 
the lacteal system. Its object is to carry the nutritious por¬ 
tion of the chyme from the digestive organs to the blood¬ 
vessels. 

72. The pulpy chyme, when it was carried from the stom¬ 
ach to the duodenum, contained the whole of the digested 
food, mixed with the secretions of the stomach. It contained 
not only all the nutritious portion of the food, which is to 
enter into the blood and nourish the body, but that which is 
innutritious and useless for the purpose of nutriment. When 
these first enter the canal, they are mixed together; but they 
are separated soon after they have passed from the stomach 
through the pylorus. 

73. In the duodenum, or the upper portion of the ali¬ 
mentary canal, the digested food is divided into two kinds 
— that which is to enter the blood-vessels, and the waste. 
The former is called chyle; the latter is useless, and must 
be passed from the body regularly each day, though in some 
persons a longer delay may be endured; but the regularity 
is necessary ; otherwise this becomes a source of irritation to 
the digestive organs, and of disturbance to all the operations 
of the frame. The chyle is a milky fluid, the same in char¬ 
acter and properties, whatever may have been the food from 
which it is extracted. “ Even in animals differing so 
widely in their aliment as the herbivorous and carnivorous 
quadrupeds, the ultimate products of digestion, in both the 
chyle and the blood, are identical in composition, in so far, 
at least, as can be determined by their chemical analysis.” * 

74. It is not known how this separation is effected, nor 
what are the processes. The liver pours its bile into the 
alimentary canal at the place where this separation is begun. 
Another gland, the pancreas, also throws its juice into the 

* Combe on Digestion, p. 63. 


4 * 


42 


PRACTICAL PHYSIOLOGY. 


same channel, at the same place. But what and how great 
influence these fluids have in this work of separation is not 
known to physiologists, nor is it necessary, for the purpose 
of this treatise, to explain the matter. It is sufficient to know 
that, in the duodenum, &c., the chyle or nutritious portion 
of the food, is extracted from the mass which has been 
digested, and that the rest is useless in the living body. 

75. The proportion of this chyle, which the lacteals are 
able to extract from the chyme, varies with the food; for one 
kind contains a much greater ratio of nutriment than another, 
as will be hereafter shown. It depends also upon the com¬ 
pleteness of digestion in the stomach; and this, in great 
measure, upon the perfectness of the mastication and mixture 
with saliva in the mouth. Of course, then, the remote 
result of imperfect mastication and hasty eating must be, 
first, imperfect digestion; second, less chyle; and, conse¬ 
quently, less nutriment for the body. 

76. The chyle, being separated from the innutritious por¬ 
tions of food, comes in contact with the inner coat of the 
canal; and here the lacteals take it up. Each absorbs almost 
infinitely small quantities; yet so numerous are they, that 
before the food has advanced far, all is absorbed. All the 
nutritious part, which can serve the purpose of eating, is then 
taken into these little tubes, and carried through these into 
the larger tubes, and next into the great lacteal duct, through 
which it is carried into the system of blood-vessels near the 
heart. 

77. Thus the work of digestion is shown to be performed 
by means of the mouth, the stomach, and the alimentary 

canal. The whole process is divided into three stages_ 

mastication and insalivation in the mouth; the digestion, or 
conversion into chyme in the stomach; the separation of the 
nutritious and innutritious parts in the duodenum. It is 
necessary that each part should be well done and in due 
order; else all that follow will be badly done. There are 
other organs concerned in this work — as the (esophagus, 
connecting the mouth with the stomach, and the lacteal ab- 


DIGESTION AND FOOD. 


43 


sorbents and ducts, that convey the chyle to the hea : . But 
the first is a mere passage-way, and the others elfect no 
change upon the matter passing through them, that would be 
useful for the general student to understand. 

78. There are other organs connected with digestion — 
the spleen, and the liver, and the pancreas; but they need 
not be described here; those who wish to study them are 
referred to more elaborate works upon anatomy and physi¬ 
ology. 


CHAPTER IX. 

Digestive Process wonderful. — We are responsible for the Selection 
and the Preparation of our Food. — Healthy Digestion comforta¬ 
ble.— Hunger not owing to Emptiness of Stomach. — Brain and 
Nerves must be sound, to perceive Hunger. 

79. This digestive process, which effects so great a 
change, is wonderful, as well as interesting. The food, 
which was of every sort, — meat, fish, bread, vegetables, and 
fruit, — mere lifeless matter upon our tables, — is now changed 
into chyle, that is homogeneous, and almost endowed with 
life. It was at first the food for the stomach : it is now nu¬ 
triment for the blood. This change is a vital one; at least 
it is effected by the fluids which are within the living body, 
and which are the product of vital or living organs. By 
what unseen agency these fluids obtain this power, is known 
only to the all-wise Creator. It is not revealed to us, nor 
need it be. Enough is revealed for our government, to 
show us our duty in regard to food and digestion. 

80 In this work, man has much to do. He is to provide 
food of suitable kinds, and must prepare it in a suitable 
manner. He is to determine the quality, and measure the 
quantity, which he shall eat. The times of his eating, and 
the intervals between his meals, are left to his discretion. 
The work of the mouth is under his control. But all the 



44 


PRACTICAL PHYSIOLOGY. 


operations of the digestive organs, beyond the mouth, are not 
submitted to his direction, nor even to his observation. 

81. When we are in good health, and the food is properly 
selected, prepared, and eaten, we are not conscious of the 
process of digestion in the stomach; but if the food be 
not properly selected or cooked, if we have not faithfully 
prepared the food, by complete mastication and mixture with 
the saliva in the mouth, for the next stage of digestion in 
the stomach, we are painfully conscious of the effort of the 
stomach to digest that which is unsuitable for its wants and 
its powers. 

82. Although we are not conscious of the process of 
digestion from any feeling that we have in the stomach 
especially, yet there is always a pleasurable sensation 
throughout the whole frame, which accompanies the proper 
and healthy performance of this function; there is a feeling 
of comfort in the body, and satisfaction in the mind, and 
usually a glow of cheerfulness attending it. One feels bet¬ 
ter, and more disposed to be contented, after his meals. 

83. Our part of this work is to select the food, and pre¬ 
pare it, by suitable combinations and cookery, for the mouth. 
Next, we are to masticate and moisten it in the mouth for 
the stomach. After this, nature takes care of it. We want, 
then, some guide to direct us in regard to the quality and 
quantity of this food, and the time and seasons for eating. 
Hunger and appetite are the first apparent guides, and with 
many, perhaps a majority of mankind, the only guides in the 
matter of eating. Hunger has been explained (§ 42, p. 27) 
to be the sensation of want of nutrition in the general sys¬ 
tem, connected with the power of digestion in the stomach, 
and with the readiness of the stomach to supply the gastric 
juice for this purpose. 

84. It is commonly supposed that hunger is a mere indi¬ 
cation of emptiness of the stomach; that as soon as the last 
meal shall have passed out of this organ, more is wanted ; 
and that as long as any food remains in it, there is no appe¬ 
tite. Neither of these suppositions i? correcl. The usual 


DIGESTION AND FOOD. 


45 


meals are digested and carried into the alimentary canal, and 
the stomach is left without food, in about three hours and a 
half, (§56, p. 33;) and if they were composed of the most 
digestible articles, this time would be much less. Yet hun¬ 
ger does not usually return in less than five or six hours. 
This leaves the stomach empty nearly half the time, without 
any craving desire of food. On the contrary, the man men¬ 
tioned in § 43, p. 27, filled and overburdened his stomach, and 
yet rose from his table hungry, and continued to feel the 
want of more food for several minutes longer. 

85. So certainly is the desire of food the result of wants 
of the system, in connection with the power of, and readi¬ 
ness for digestion, that in some diseased states of the system, 
where both these conditions exist, but no communication 
between the stomach and the blood-vessels, the appetite is 
ravenous. When the lacteal tubes are diseased, the passage 
through them is interrupted, and no chyle can pass from the 
digestive organs to the veins; consequently, however large 
the quantity of food that is eaten, and however well this may 
be digested, still none of it passes into the blood, and the 
body is not nourished. The changes of particles go on; the 
old ones die, and are carried away; but the blood has no 
means of supplying their place with others, that are living 
and new. The flesh wastes away, and craves nutriment. 
The stomach is healthy and able to digest, and, answering to 
the call of the general frame, gives the sensation of hunger. 
The want is not supplied; its cry is not stilled, except so 
long as the stomach is full. There comes, therefore, in these 
cases, a voracious desire of food, as soon as the stomach is 
empty. 

86. The wants of the whole body for more nutriment are 
communicated first to the stomach, and thence to the brain. 
Here is the real sensation of appetite. It therefore is neces¬ 
sary, not only that the stomach should be in sound condition, 
but also that the brain be in a condition to recognize this 
feeling of want. This feeling is conveyed through the nerves 
from the stomach to the brain, and there perceived and rec- 


46 


PRACTICAL PHYSIOLOGY. 


ognized. If, then, the nerve of the stomach be diseased or 
divided, there can be no communication from this organ to 
the brain, and hence no sensation conveyed, and no hunger 
felt. Some physiologists have tried the experiment of cutting 
the nerves which connect the stomach with the brain in dogs. 
The consequence was, that the animals seemed to have lost 
all sensation of appetite, and although they had been long 
deprived of food, and were really in need of it, they did not 
appear to feel or to understand the want of it. 

87. The appetite, then, is felt in the brain; but it is not 
perceived, nor are we conscious of it, unless we can give 
attention to it. It not unfrequently happens that one is so 
intently engaged in any pursuit, that he forgets his hours of 
eating and his own necessities. Students are sometimes so 
devoted to their books, that their meals do not occur to them. 
Men who are absorbed in any care or anxiety pay less than 
due attention to, and do not perceive, their craving sensations. 
Sailors, in times of peril and shipwreck, may go from morn¬ 
ing till night without thinking of dinner. The anxious 
mother, watching over a sick child, needs often to be re¬ 
minded by others of the time and necessity of eating. 

88. A friend of mine, whose business, during the whole 
day, is in the city, and whose employment often absorbs his 
whole attention, sometimes returns at night to his home in 
the country with a great appetite; for he has been so much 
occupied that he has forgotten his dinner. And when thus 
engaged, it is only at night, when business hours are passed, 
and his occupation has ceased, that he gives any heed to the 
wants of his system, or discovers that he is hungry; and 
then, from his previous exhaustion and want of supply, his 
hunger returns with double force. 

89 In these and in similar cases, one may not feel appe¬ 
tite sufficient to warn him of the hours of eating, although, 
at the same time, his system is in want of nutriment, and 
there is real cause of hunger without the sensation. For 
the body is suffering from the waste of its particles and from 
the privation of food; the stomach is empty, and it has sent 


DIGESTION AND FOOD. 


47 


the warning of this emptiness to the brain; but if this organ 
gives no attention to it, no sensation is felt, nor hunger per¬ 
ceived. This happens for the same reason that, when we are 
sometimes absorbed in thought, we do not hear the church 
clock strike, although very near us, or even the house clock 
in the same room with us. In this case, the impulse was 
given to the air, and communicated to the tympanum of the 
ear, but the brain was directing its attention elsewhere, 
and perceived no sound. 


CHAPTER X. 

Appetite affected by State of Mind. — No Digestion without Appe¬ 
tite.— Appetite not always a Sign of digestive Power. — Appetite 
and Taste not identical. — Great Privation of Appetite. 

90. The appetite is affected by the state of health both of 
the body and of the mind. In fever, in pain, and in certain 
dyspeptic states, the stomach craves little or no food. So, 
in mental distress, in times of great fear or sorrow, or ex¬ 
treme anxiety, the appetite fails. Even in a single moment 
the appetite may be suspended by any sudden mental affec¬ 
tion or emotion. If any one sit down at a table with even a 
strong desire of food, and if, when about to eat what seems 
to him inviting, he should be told of the death or extreme 
danger of a near friend, at once all appetite is gone; food is 
no longer inviting. Let him hear the cry of fire or of dis¬ 
tress near by, and the same result happens. The stomach 
suddenly ceases to make its cravings known, and appetite 
and food are immediately forgotten. I have known one to 
refrain from telling a friend bad news until after eating, 
“ lest he should spoil his dinner.” 

91. Hunger is given to us as a guide to our duty in the 
work of sustenance; and when properly regarded, it is a 
safe guide. It indicates the wants of the system for more 
nutriment. Even in a good state of health, these wants vary 



48 


PRACTICAL PHYSIOLOGY. 


with many outward and inward circumstances. They differ 
with the manner of life, and with the quantity and energy of 
exercise. The laborious and active have more hunger than 
the idle and the slow. Children and youth who are growing 
in stature, convalescents who are regaining lost flesh, have 
more imperative appetites than others. Appetite is more 
keen when the body is in full vigor, and all the functions 
are performed with the most energy. When the blood flows 
freely and the muscles play smoothly, when the mind is 
buoyant and the spirit joyous, the appetite boldly indicates 1 
a want of food in the whole system, and a ready power of 
the stomach to digest it, and convert it into the nutriment 
of the blood. 

92. Appetite is usually the sign of digestive power. Cer¬ 
tainly there is no vigorous digestion without it. When the 
digestive organs, nerves, and brain, are apparently in good 
condition, and we are attentive to the warnings of the stom¬ 
ach, if then we feel no hunger, we may be assured that the 
stomach craves no food because it cannot digest it. How¬ 
ever long it may have been without food, if it do not by its 
hunger declare its readiness and ability to convert it into 
nutriment for the blood, it is useless to eat. It is even worse 
than useless; for whatever is then eaten cannot be changed 
to pulpy chyme, nor to milky chyle, nor can the lacteals ex¬ 
tract from it nourishment to feed the exhausted blood, or the 
wasted body. Food, then, eaten when we are not hungry, 
gives weakness and oppression, and not strength and vigor. 

It causes pain rather than the feeling of comfort, that follows 
or accompanies good digestion. 

93. On the other hand, appetite is not always evidence of 
digestive power. In some states of dyspepsia there is a vo¬ 
racious desire of food, without corresponding power in the 
stomach to digest it. There is sometimes a diseased and 
continual irritation in this organ, which suggests to the brain 
the want of food as the only means of allaying it. If food, 
m these cases, be eaten according to the appetite, — or if, in 
some cases, any food be taken, however urgent the hunger,— 


DIGESTION AND FOOD. 


49 


indigestion and pain will surely follow. Very frequently, 
during convalescence from fevers, the appetite returns before 
the power of digestion. The body is wasted with disease, 
and wants a great quantity of nourishment to restore its loss. 
The fever has gone; the stomach is free from nausea, but 
yet it is uneasy, and craves a large supply of nutritious food. 
But it has not regained its full strength. It can no more 
digest a full allowance of hearty food than the muscles or 
limbs can perform the full day’s labor of a man in health. If 
the convalescent should eat a strong man’s food, as appetite 
suggests, pain and weariness will fall upon his digestive or¬ 
gans as inevitably as they would upon his limbs if he should 
do a strong man’s work. 

94. Appetite and taste are not the same. It is a mistake 
in our self-management to confound the one with the other. 
One is a desire for food corresponding to the wants of the 
system ; the other is mere pleasantness of the food while in 
the mouth. In domestic economy, when the array of suc¬ 
cessive dishes of various kinds comes before us, when all are 
delicious and tempting, and pleasant to the palate, there is 
danger of eating of one, and then another, to gratify the taste, 
even after appetite has been satisfied. It is, therefore, impor¬ 
tant to distinguish between the sensation of the stomach 
which implies the want of nutriment, and which is real hun¬ 
ger, and that mere sensation of the mouth which implies 
merely the want of something pleasant to the palate, and 
which is factitious hunger. 

95. There are remarkable instances of absence of appe 
tite under disease or excitement. I have known persons in a 
high state of mania, when the mind was violently excited or 
absorbed, to endure entire abstinence from food or drink for 
three days. During this time, they could not be persuaded 
to take a morsel to eat or a drop of fluid. In these and sim¬ 
ilar cases, there were undoubtedly want of nourishment in the 
body, and power of digestion in the stomach. The appetite 
was suspended, because the brain had its attention intently 
fixed upon its delusions and distress. But when the excite* 


50 


PRACTICAL PHYSIOLOGY. 


ment was calmed and the distress alleviated, the sufferer was 
persuaded to eat, and ate with the usual freedom, and digested 
with the usual ease and comfort. 

96. Some extreme instances of this are on record. “ One 
is published in the Edinburgh Medical Essays for 1720, of a 
young lady about sixteen years of age, who, in consequence 
of the sudden death of an indulgent father, was thrown into a 
state of tetanus, or rigidity of all the muscles of the body, 
and especially those of swallowing, accompanied with a total 
loss of desire for food, as well as incapacity for swallowing it, 
for two long and successive periods of time—in the first in¬ 
stance for thirty-four, and in the second for fifty-four days; 
during all which time of her first and second fastings, she 
declared she had no sense of hunger or thirst, and when they 
were over she had not lost much flesh.” * 

97. The celebrated Miss Ann Moore, of Tutbury, Eng¬ 
land, lived for some years on so little food, that she w r as sup¬ 
posed to live entirely without it; and she even pretended 
that she was able to lire without any food whatever. A very 
intelligent committee, who watched her carefully, could detect 
nothing but a little tea that was given her. A woman, in 
consequence of lockjaw, swallowed nothing but a very little 
cold water for four years; and for twelve years afterward, 
took no more food than is sufficient for a child two years old. 


CHAPTER XI. 

Great Eaters.— Causes of enormous Appetite and Eating. — Stom¬ 
ach distended by Over-eating. — Hunger recurs when Blood wants 
more Chyle. — Intervals between Meals vary with Circumstances. 
— Disturbance of the usual Hours of Eating disturbs Digestion. — 
Intervals of Meals. 

98. On the contrary, there are instances of persons who, 
from disease or perverse habit, have acquired an extraordi- 


Good’s Nosology, p. 16, note. 



DIGESTION AND FOOD. 


5 ) 


nary and almost insatiable appetite for food. With them 
hunger seems to be ever present. The stomach full of food 
hardly allays the desire for more, or only suspends it for a 
short time. A case is recorded, in the “ Philosophical Trans¬ 
actions,” of “ a boy of twelve years of age, who had so 
strong a craving that he would gnaw his own flesh when not 
supplied with food. When awake; he was constantly devour¬ 
ing, though whatever he swallowed was soon afterwards 
rejected. The food given him consisted of bread, meat, 
beer, milk, water, butter, cheese, sugar, treacle, (molasses,) 
puddings, pies, fruits, broth, potatoes; and of these he swal¬ 
lowed in six successive days three hundred and eighty-four 
pounds two ounces, avoirdupois — being sixty-four pounds 
a day on an average. The disease continued for one year.” * 

99. In a recent paper printed by the Statistical Society of 
Manchester, England, relative to the character and condition 
of the laborers employed in the construction of railways, Mr. 
Rawlinson says, “ Some of the most brutal and daring men 
had taken to this mode of earning a livelihood, and, obtaining 
three or four times as much money as they had ever earned 
before, they entered into all the worst vices of the worst 
men. One of them stated to me, afterwards, that he had de¬ 
voured, seven pounds weight of meat , and drank nine quarts 
of gin , and all mixed , in one day; and that he invariably 
drank all his wages.” 

100. This enormous appetite does not always depend 
upon the wants of the system, but in some cases, as in the 
boy, § 98, upon disease. In others it is caused by indulging 
the perverse habit of voracious eating. Great eaters feel the 
want of a large quantity in the stomach. They are no bet¬ 
ter nourished than those who eat less; but, without a great 
supply, they feel hollow, faint, and languid. The stomach, 
being used to this great distention, does not act easily upon 
a small quantity. In some persons, the stomach, being once 
distended, does not recover its original size. Dr. Darwin 
states that “ a woman near Litchfield, England, who ate 


Good’s .Nosology, p. 16, note. 


PRACTICAL PHYSIOLOGY. 


52 

much animal and vegetable food for a wager, affirmed that, 
since distending her stomach so much, she had never felt 
herself satisfied with food, and had in general taken twice 
as much at a meal as she had been accustomed to before she 
ate so much for a wager.” * 

101. This is an extraordinary instance of extreme disten 
tion of the stomach; but it is not unusual to find similar 
conditions, though in a less degree, produced by smaller er¬ 
rors of the same kind. This unnatural state of the stomach 
comes oftener from a long and gradually-increased indul¬ 
gence in great eating, amounting sometimes to gluttony, than 
from a single gormandizing, as in the case of the woman 
stated in the last section. But it is an error that creeps on 
very insidiously, and with a seemingly good cause ; and one 
who begins to trespass in this way is in danger of repeating 
the mistake, and of increasing the evil continually, without 
suspecting he is doing any more than obeying the natural 
laws of his sensations, and supplying his proper wants. 

102. As soon as any of the food is digested and reduced 
to chyme, and sent into the duodenum, the innumerable lac- 
teals commence their work of absorbing or taking up the 
chyle — the nutritious portion —and carrying it to the veins. 
They continue this work for several hours, more or. less, ac¬ 
cording to the fulness of the storehouse of nutriment; and 
during this time, they replenish the waste of the blood, and 
enable it to supply the wants of the whole body. After a 
varying period of some hours, the quantity of chyle is ex¬ 
hausted in the alimentary canal, and can furnish no more 
material for the blood, and the blood can no longer meet the 
demands of the wasting flesh. Then there is a want of 
more and new nutriment — a craving for food in the stomach, 
and a consequent sensation of hunger, and we need to eat 
again. 

103. The period for the return of appetite , or the proper 
interval between the hours of eating, depends upon many 
circumstances and conditions, such as the temperament, the 

* Zoonomia, Yol. II., p. 107. 


DIGESTION AND FOOD. 


53 


age, and the habits of the person, and the quantity and di¬ 
gestibility of the food previously eaten. The nutriment 
would be earlier exhausted, and hunger sooner return, after a 
light meal of innutritious food, than after a full meal of rich 
food. The young and growing need food oftener than the 
mature and full-grown, and the convalescent oftener than 
the permanently healthy. The expenditure of life and the 
waste of particles are more rapid when we are in motion 
than when we are still. Consequently the active and labori¬ 
ous are sooner exhausted, and need to be earlier recruited, 
and should eat more frequently than the slow and indolent. 
The sanguine and the nervous, for the same reason, are more 
impatient of hunger than the lymphatic and dull. 

104. The return of appetite is very easily trained to reg¬ 
ular habits, so that it comes at about the usual time of eating; 
and until that hour, whatever it may be, hunger is not felt. 
At the usual hour of eating, appetite becomes perceptible, 
and, if not then gratified, it may become urgent; or some¬ 
times it ceases till the next time of eating. The stomach, 
being trained to observe these hours, accommodates its wants 
to the periods of supply. Those who dine at twelve feel the 
want of food at that hour; while those who dine later, what¬ 
ever may be the season, are not often disturbed with hunger 
until their usual time of eating comes round, and then they 
feel the want of food. 

105. This power of the stomach to accommodate itself to 
the habits of life, is not only manifested in different persons, 
who have been differently educated from the beginning, but 
it is shown in the same individual at different times. We 
not unfrequently see an entire change of habits of the same 
stomach, arising from change of manner of life. 

106. Some have always been accustomed to dine at twelve, 
and always felt hungry at that hour. Suddenly, they change 
their residence and their hour of eating, and wait till one or 
two o’clock for their dinner. The stomach does not change 
its habits and wants so speedily. At first, and for some time, 
the appetite returns at the former hour of indulgence, and 

5 * 


54 


PRACTICAL PHYSIOLOGY. 


waits impatiently for its food ; but gradually it accommodates 
its wants to the new regulation, and hunger waits quietly till 
the newly adopted hour. Again, the same persons have sud¬ 
denly returned to their early hours, but the stomach does not 
go back so readily; at first, it was not in want of food at 
twelve; but in a short period, finding its supply come early, 
it manifested an early want, and became hungry at twelve. 

107. Whatever the accustomed hours of eating may be, 
the stomach does not bear sudden changes, nor even a 
change for a single meal, without some complaint. My pres¬ 
ent usual hour of dining is one o’clock. My appetite 
returns at that time; my stomach then craves food, and the 
gastric juice is ready to flow and dissolve it. If this want is 
gratified, my dinner is digested easily, and I feel comfortable 
and prepared for business during the afternoon. But if, for 
any cause, I vary from my regular habit, and eat at a later or 
earlier hour, my digestion is not so easy, and my body and 
mind are not so free for labor. 

108 Yesterday I was occupied abroad, and did not return 
to my dinner until three o’clock. I felt more hungry than 
usual. But, after I had eaten, my stomach reminded me that 
it did not perform its work with its customary ease. My 
body was not so light and buoyant, my brain was not so clear, 
as usual; I could not apply my mind with its accustomed en¬ 
ergy to its work. And the result of the afternoon’s labors 
was less than on other days. The same has generally hap¬ 
pened at other times, when I have postponed my dinner 
beyond its accustomed hour. I feel the same loss of energy 
and of command of my powers, whenever I anticipate the 
hour and dine at twelve. If I had been a mechanic, I should 
have had the same difference in the precision and success with 
which I could use my tools; or, if I had been a farmer, 
there would have been the same failure in the energy and 
effect of wielding the axe, swinging the scythe, or striking 
with the hoe, after such a disturbance of the hours of eating. 

109. Some families have no regular hours of eating. 
They eat whenever it suits the convenience of the cooks to 


DIGESTION AND FOOD. 


55 


prepare the meals, or of the household to eat them. These 
are varied, and often vary widely, to meet the plans and the 
accidents of business. These people dine sometimes very 
late, and at other times very early. There are many em¬ 
ployed in cities at a distance from their homes. They do 
not return at noon, nor do they dine at any regular boarding 
place; but they eat at eating-houses, at any hour, when the 
business of their shops, their stores, or their offices, gives them 
leisure. Occasionally, for want of time, they omit their 
dinner entirely. All these irregular habits of eating disturb 
their regular habits of digestion, and consequently leave them 
with somewhat less power of application and labor for the 
next succeeding hours. 

110. In general , the intervals of the meals , during the 
active part of the day , should not he more than six or seven 
hours. Dinner should follow the morning meal, and supper 
should follow the noon meal, within this period. The fre¬ 
quency of eating should follow the law of appetite, described 
in §§ 102, 103, p. 52; and, regarding this law, children and 
laborers should have shorter intervals, and eat more fre¬ 
quently than the mature and the inactive. 


CHAPTER XII. 

Breakfast should be soon after rising. — If it be late, a Lunch should 
be taken early in the Morning. — Health better sustained when 
full. — Breakfast should be before Labor or Exposure. — Hour of 
Dinner. — Interval between Breakfast and Dinner. — Forenoon 
Lunch good in some Cases. — Needed by those who breakfast 
early and dine late. — Night Suppers injurious. — Summary of 
Meals. 

111. During the hours of sleep, there is no action of the 
body, and consequently little waste; therefore the interval 
between the evening and the morning meal may be longer 
than the interval between the meals which are taken in the 
active part of the day. Yet the store of nutriment in the 



56 


PRACTICAL PHYSIOLOGY. 


digestive organs and the blood-vessels becomes exhausted 
during the night, and the system needs more food before 
any considerable amount of action is undertaken in the 
morning; for the frame is not then prepared to bear any 
more drafts, and it must be recruited before it can undergo 
any severe labor. The breakfast should therefore be taken 
soon, within an hour after rising. This is especially requi¬ 
site for invalids, who have not much strength, and but little 
power of endurance. 

112. When the morning meal is not to be eaten early, 
some light refreshment at the time of rising will meet the 
immediate wants of the system, and sustain it during the 
morning exercise. It is well, then, if some considerable 
time is to elapse between rising and breakfast, to take some 
food early. This is a common custom among the Creoles 
of Louisiana and the inhabitants of Cuba, and some classes 
of people in France. These have coffee, fruit, or other light 
food sent to their sleeping-rooms, sometimes before, and 
sometimes after rising, which, they think, enables them the 
better to sustain any fatigue before the regular breakfast is 
given them. 

113. The animal system sustains all action , labor , and 
exposure best when it is well nourished. When the nutri¬ 
ment fails, it becomes sooner fatigued, and more susceptible 
of pain; and, besides this, it is more liable to suffer from 
any causes, which would impair its soundness or diminish 
its vitality. The- contagion of disease, the infection of fever, 
whatever may bring on disorder, act more readily and pow¬ 
erfully on the hungry, and on those who are badly nourished, 
than on those who are well fed. We are better able to resist 
the influence of cold, and to maintain the natural temperature 
of the body, when we are full, than when we are fasting. 

114. All these causes of disorder or suffering act upon 
the human constitution with more destructive force before 
breakfast than afterward. On this account, all who are 
about to expose themselves to any of these morbid influ¬ 
ences, to contagion or infection of disease, or to such 


DIGESTION AND FOOD. 


57 


exhalations of marshy countries as produce fever and ague 
or other malady, should eat their breakfast before going 
abroad. Travellers and others, who go abroad in winter, 
or in stormy weather, will maintain their heat better and 
defend themselves more effectually against the elements, if 
they breakfast before they go out. But if they go out in the 
morning hungry, they suffer much more from chills and 
dampness, and are in greater danger of taking cold. 

115. If this precaution of early eating be requisite for 
the healthy and the robust, it is much more so for the 
feeble and the invalid. Inasmuch as those, whose strength 
and vitality are in any way reduced below the average stand¬ 
ard, are more susceptible of disorder from any disturbing 
cause, and are more easily fatigued with labor, it is more 
necessary for them than for others to strengthen and defend 
themselves with the early morning refreshment, before they 
engage in laborious occupation, or expose themselves to cold 
or infection. 

116. The time of the dinner differs very materially in vari¬ 
ous nations, and among people in different places of the same 
nation. Three hundred years ago, the king of England and 
his court dined at eleven. Some of the nobility, previous to 
that time, breakfasted at seven, dined at eleven, and supped 
at four. More recently, both in America and Europe, 
twelve at noon was the established hour; and at present, in 
the rural districts, almost every where, this dining hour is 
still observed ; while in towns and cities the time varies from 
one to six or seven. But, in families who dine so late, 
breakfast is also late, and the interval between the first and 
second meal is not so wide as the lateness of the dining hour 
would seem to indicate. In about five or six hours after the 
morning meal, the appetite returns, and the system calls for 
new refreshment. This is the true guide for the time of 
dining. Whatever may be the hour of breakfast, not more 
than about six or seven hours should elapse, before the sys¬ 
tem is again refreshed with food. 

117. In some of the European cities, breakfast is suffi- 


58 


PRACTICAL PHYSIOLOGY. 


ciently early, but the dinner is taken as late as six or seven 
o’clock in the evening. This would leave an interval of 
eight to ten hours between the first and second meals, which 
is a much longer space for fasting than the time specified in 
the last section, and longer than the system can well endure 
without suffering from want of nutriment. Many — probably 
most of those who dine so late — remedy this difficulty by 
interposing a lunch between the first and second meal in 
the day. This is, with most people, a light meal, and in¬ 
tended merely to sustain nature through the long interval 
of the morning and noon; but with some it is composed of 
heavy and substantial food, such as would ordinarily be 
taken for dinner. 

118. A lady went from Boston, in September, 1846, to 
London. Her usual dining hour had been two, at home; but, 
in London, it was suddenly changed to six or seven o’clock. 
Her morning meal was also postponed somewhat; yet the in¬ 
terval between these was several hours longer than she had 
been accustomed to. In a few weeks, she suffered materi¬ 
ally in health, and became much debilitated, and consulted 
a physician, who advised a lunch to be taken in the fore¬ 
noon. Following his advice, she soon recovered her wonted 
health and strength. A similar case occurred in New Or¬ 
leans. A friend suffered in the same way, from the same 
cause, and was restored by a similar change in his hours of 
meals. 

119. Growing children, and persons recovering from 
sickness, and men engaged in very hard labor, may do well 
to take this forenoon lunch, even if the interval between the 
morning and noon meal be not more than six or seven hours. 
And healthy men, in ordinary pursuits, would do it with ad* 

- vantage, if they breakfast early and dine very late. But for 
mature persons, in good health, who are not engaged in 
very hard labor, and whose dinner is not delayed more 
than six or seven hours from the breakfast, the stomach is 
better if at rest until the hour for the regular meal 
round at noon. 


comes 


DIGESTION AND FOOD. 


59 


120. The supper is usually a lighter mtvd, and is needed 
for all who have not already eaten three times. It is the 
almost universal custom of the civilized nations to eat three 
times a day. Remembering the rule before stated, (§ 110, 
p. 55,) that not more than six or seven hours of active 
life should elapse before the refreshment of food, and that it 
should not usually be taken oftener than this, it is easy to 
determine whether any supper should be taken after dinner 
or not. If the dinner be as late as six or seven o’clock, and 
there has been a lunch taken in the forenoon or at noon, the 
fourth meal will be unnecessary. When the dinner is at or 
near night, so late that there will be not more than four or 
five hours between this meal and bed-time, then the supper, 
if taken before sleeping, would be not only needless, but inju¬ 
rious. It is not then wanted for nutrition, and the stomach 
is not in a condition to digest it. The supper, therefore, 
should depend upon the distance of the sleeping hours from 
the dinner. So that he who dines at twelve and retires at 
nine, and he who dines at seven and retires at four, both 
equally need the evening or the night meal. 

121. But supper should he eaten usually about three 
hours or more before sleeping. Sleep is the rest of all the 
voluntary powers; then nothing but the lungs and the heart 
keep in motion; all the others are still. The mind, the 
feelings and the affections, the brain, the muscular and 
digestive organs, all need and enjoy this rest. If any of the 
organs or powers are not permitted to repose, the sleep is 
not profound; the rest is not entire. If, then, we eat so late 
that the food be not digested before we retire to our beds, the 
digestion is still going on while we attempt to sleep, and the 
sleep is disturbed by it; then dreams — sometimes distressing 
dreams — oppress and weary us, and the body and mind are 
not refreshed completely for the following day’s labor. 
Second suppers are therefore injurious. 

122. The general custom of three meals a day — a good 
breakfast soon after rising in the morning, a fuller and more 
nutritious meal near the middle of the active part of the day, 


GO 


PRACTICAL PHYSIOLOGY. 


and a lighter meal a few hours before sleeping — meets the 
wants of the body, and corresponds with the powers of diges¬ 
tion. But when we add to these, lunches during the day, 
or take a supper of feasting for hospitality or self-indulgence 
at night, we overstep the demands for nourishment, and 
overtask the powers of digestion, and prevent the full, 
refreshing effects of sleep at night. 


CHAPTER XIII. 

Quantity of Food. —Fleshy Persons not always great Eaters. — Lean 
Persons not always small Eaters. — Action causes Changes of Par¬ 
ticles.— Laborers eat more than the Sedentary. 

123. The quantity of food, as we shall see hereafter, is 
not to be governed by a fixed law. Men differ in their 
wants, and their necessities, and their powers. In America, 
where food is abundant and cheap, there are few who do not 
eat enough; there are more who eat too much. It is gener¬ 
ally supposed that Americans err in excess; and medical ob¬ 
servers and writers think that in no country is the stomach 
so frequently disordered as here. We seldom or never hear 
of an individual who weighs and measures his own food, day 
by day, to know how much he eats; but in some public estab¬ 
lishments, as the army, navy, prisons, and some workhouses, 
the dietetic code determines strictly the quantity and the 
kinds of food that shall be given to each one. 

124. The seamen in the British navy are allowed 1 lb. 
bread, 1 lb. fresh meat, £ lb. vegetables; and, when fresh 
meat and vegetables are not given, | lb. salt meat and f lb. 
flour are allowed, being 40 oz. solid food for each day’s 
support. The dietary for emigrants going from Great Britain 
to the East Indies and New Holland gives 9 oz. animal 
food, 12 oz. bread, 4 oz. flour, 2 oz. rice, 1 oz. raisins; in 
all, 28 oz. per day. The soldiers of the army of the United 
States are allowed to have £ lb. pork or bacon, or l£ lb. beef 



DIGESTION AND FOOD. 


61 


fresli or salt, 18 oz. bread or flour, or 12 oz. hard bread, or 
l£ lb. corn meal, a day besides 8 qts. of peas or beans, or 10 
lbs. of rice, for every hundred days. 

125. The quantity of food must vary with the habits of 
the individual, and with the energy and quantity of exercise. 
Some have a much greater nutritive power than others. 
Some extract more nutritive chyle from a given amount of 
food than others. Fleshy persons are not always great 
eaters, nor are all lean persons proportionately limited in 
their quantity of food. On the contrary, there are many 
instances of great corpulence connected with an extremely 
small diet, and some cases where the greatest temperance in 
food does not prevent or diminish the fatness. On the other 
hand, there are some persons whose appetite is ever ready, 
and digestion apparently good, and who consume much more 
than the average quantity of aliment, and yet are miserably 
lean. 

126. A young woman, whose body was full, round, and 
almost fat, came under my observation a few years ago, on 
account of neuralgia. The pain was, for a long time, fixed 
in the stomach, and then she could only eat a single cracker, 
or an equal amount of bread, weighing less than one ounce 
a day. Yet her nutritive powers were so good, that, with 
this small quantity of food, she maintained her full condition, 
and showed no sensible loss of flesh. She continued this 
spare diet for about six weeks, and, in all this time, retained 
her healthy plumpness of form. She was not strong, and 
yet she was not very weak. She was not confined to her 
bed, nor to her chamber, but was able to be about the house, 
and perform the light household work. In her best state of 
health, she was a small eater; but she was then strong and 
vigorous, active and fleshy. 

127. The requisite quantity of nutriment varies more with 
quantity and energy of action which the system is called 
upon to sustain. All motion is connected with waste from 
the body; the vitalized particles exhaust their vitality in the 
process of action, and a change then takes place. The old 

6 


62 


PRACTICAL PHYSIOLOGY. 


and exhausted particles, having lost their living principle, are 
then removed from their places in the textures of the body, 
and thrown into the veins, and thence carried away. Their 
places must be supplied by new particles from the blood, 
and the blood receives these from the digested food. T. he 
body of the laborer, therefore, undergoes more rapid waste, 
and needs a greater and more frequent supply of food, than 
that of the people of sedentary habits, or idlers. It is a great 
mistake, then, to suppose that all men, in whatever occupa¬ 
tion engaged, should eat the same quantity of food. The 
British government give to the troops, on their voyage to the 
East Indies, on account of the quietness of their life, ten per 
cent, less of solid food than to the sailors, who are in con¬ 
stant action on board the same ships. 

128. For this reason , the same man should not eat the 
same quantity in all varieties of exercise. At one period, 
he may be very laborious: he then wants more food than at 
another time, when he may be engaged in lighter employ¬ 
ment. This principle ought not to be forgotten by those 
who make permanent changes in their occupations. Change 
of habits presupposes change of nutritive wants. If the 
action of the body be reduced, there is a reduction of waste, 
and of nutritive want and digestive power. But, unfor¬ 
tunately, the appetite is not readily reduced, nor is it per¬ 
fectly easy to control it at once. But this is necessary, in 
order to prevent indigestion. 

129. Some young men, who have been accustomed to active 
exercise, or even hard labor, suddenly change their occupa¬ 
tions. They leave their farms or their workshops, and go to 
school or to college, or to the lighter employment of cities. 
Their habits of eating have been very properly adapted to 
their habits of labor. While they were hard workers, they 
were hearty eaters. Too frequently, their full diet is retained 
after their hard labor of body is discontinued, and they still 
eat the same amount of food as before. This is more than 
the system now requires, and more than the stomach can 
digest. That quantity, which was no more than sufficient to 


DIGESTiuN AND FOOD. 


63 


sustain a life full of vigorous and laborious action, is too 
much for the inactive and sedentary life, and even becomes 
oppressive and injurious. 

130. Hence men complain of indigestion and of loss of 
health in other ways, when they have become less active. 
The real ground of difficulty is not so much that their new 
occupations are necessarily injurious to digestion, as that the 
quantity, and often the quality, of food is not adapted to their 
altered habits. In the new occupation, there is less action, 
and consequently less waste, and of course less use and 
demand for food, and, necessarily connected with these, less 
digestive power. When these new conditions are disre¬ 
garded, and the old habits of eating continued, the stomach 
is overburdened, and dyspepsia follows, with its usual train 
of evils. 

131. It is not unfrequent at Cambridge — and I believe it is 
the same at other colleges — for some of the most industrious 
students to leave on account of ill health. These unfor¬ 
tunate invalids are more among the older than among the 
younger portions of the classes. And the reason is plain. 
Most of these were not originally destined to literary pursuits, 
and were engaged, in their earlier years, on their farms, or 
in their workshops, or other spheres of active employment. 
They were generally strong and healthy, but, having a de¬ 
cided inclination for the study of books, they changed their 
active habits of body for the quietness of the student’s life. 
But their appetite and diet continued the same, and thereby 
they fell. Others were younger, and went through college 
with less suffering and fewer failures of health. These had 
never been laborious, nor had they acquired the habits of 
eating which laboring men should have. Their habits were 
always adapted to their present circumstances, and conse¬ 
quently they were spared, at least, this cause of ill health. 

132. Men and women who have reached the fulness of 
stature, cannot safely indulge the habits of eating which were 
proper for them while they were growing. The quantity of 
food which was necessary to supply the growth in youth, is 


64 


PRACTICAL PHYSIOLOGY. 


more than is needed in mature years. And not only is it not 
needed, but it is a burden to the system, and imposes an in¬ 
jurious tax upon the powers of the stomach to digest it. As 
soon, therefore, as the body ceases to grow, the diet should 
be reduced from the fulness of youth, and accommodated to 
the more limited wants of the system. Convalescents, very 
properly, eat a greater quantity while they are recovering lost 
flesh, in order to meet the new conditions, and supply the 
new wants of the system; but the moment they have 
regained their usual fulness, they should return to their 
usual diet. 


CHAPTER XIV. 

Quantity of Food determined by the Wants of the System and the 
digestive Power. — Measured thus only when we eat slowly.— 
Each one must judge for himself how much he shall eat. — Excesa 
of Food oppresses and weakens. — Due Quantity strengthens.— 
Time saved by hasty Eating more than lost by Oppression after¬ 
ward. — Rapid Eating at Hotels and on Steamboats. 

133. It has been shown, (§§ 39, 40, pp. 25,26) that, when 
the whole system is in good health, the digestive powers of the 
stomach correspond to the nutritive wants of the body; that, 
when the body is in want of nourishment, the stomach pre¬ 
pares, or is ready to prepare, gastric juice sufficient to dissolve 
as much food as is needed, and no more; and that this quan¬ 
tity of gastric juice gives us the measure of the food which 
should at any time be taken. If we could then ascertain this 
quantity of gastric juice, we should have no difficulty in 
determining the requisite amount of food. In St. Martin 
(§ 35) P- 23) the flow of this juice could be seen through the 
aperture, and its quantity ascertained; but we can only obtain 
this knowledge by carefully watching our own sensations. 

134. When the body wants nourishment, and the stomach 
is ready to pour out gastric juice and digest it, there is a sensa¬ 
tion of hunger, (§ 42, p. 27;) and this sensation continues as 



DIGESTION AND FOOD. 


65 


long as there is any of this gastric juice unoccupied by food, 
or until the inner coat of the stomach has poured out as 
much as it can give at the time. So long as this sensation 
continues, there is a call for more food, and more can be 
digested. We may safely eat, then, until this natural appetite 
ceases, provided we throw the food into the stomach no 
faster than the digesting fluid is ready to dissolve it. Mr. D. 

43, p* 27) did not even eat until his hunger ceased; and 
yet he ate more than his gastric juice could dissolve. 

135. In order , then , to adapt the food to the wants of the 
system and the power of digestion , we must eat slowly; we 
must masticate each morsel patiently and thoroughly in the 
mouth, waiting, in this manner, before we swallow this, until 
the previous morsel has had time to combine with the gastric 
juice in the stomach So doing, we can determine whether 
that organ wants or is prepared for another; and, when that 
demand ceases, we can suspend the eating. Then we shall 
have eaten all that is needed for nutrition, and no more than 
the stomach can digest. 

136. This will require us to eat, not to fulness, as is 
unhappily too commonly done; nor even to satiety, for that 
would overstep the wants of -nature; but merely until the 
demand for nutrition ceases. Dr. Beaumont says, “ There 
seems to be a sense of perfect intelligence conveyed to the 
brain, which, in health, invariably dictates what quantity of 
aliment,(responding to the sense of hunger and its due satis¬ 
faction), is naturally required for the purposes of life, and 
which, if noticed and properly attended to, could prove the 
most salutary monitor of health and effectual preventive of 
disease. It is not the sense of satiety; for this is beyond the 
point of healthful indulgence, and is Nature’s earliest indica¬ 
tion of an abuse and overburden of her powers to replenish 
the system. It occurs immediately previous to this, and may 
be known by its pleasurable sensations of perfect satisfaction, 
ease, and quiescence of body and mind. It is when the 
stomach says, Enough. It is distinguished from satiety by 
difference of sensation; the latter says, Too much” 

6 * 


66 


PRACTICAL PHYSIOLOGY. 


137. The wants of nutrition, even in men in good 
health, depend upon so many circumstances,—their exer¬ 
cise, exposure, and their temperament, — and the digestive 
powers differ so widely in different people, that we could 
scarcely find two who require exactly the same quantity of 
food, nor would the same man require the same quantity at 
all times. Therefore it is impossible to prescribe any exact 
weight or measure, which all should eat. But every one 
who learns the principles which have been stated here, who 
examines the circumstances of his own life, and carefully 
watches his own sensations, will be better able to determine 
now much he shall eat. If then, he faithfully obeys the law 
of nutrition, and applies it rigidly to his own self-management, 
he will not err in his diet. 

138. When a man eats sufficiently, and no more, — when 
his stomach has received no more than it can easily digest,— 
he feels refreshed and easy ; he soon becomes light and buoy¬ 
ant, and is then ready to recommence his active business. 
But when the stomach has more than it can easily convert into 
chyme, it is oppressed with labor, and feels a dead weight 
bearing it down. All the energies of the body are then con¬ 
centrated in the effort of the stomach to perform its extraor¬ 
dinary labor, in the same manner as all the energies of the 
system are concentrated in the extraordinary muscular exer¬ 
tion, when we attempt to lift great weights, or to run a race. 
While the digestive organs, or the muscles, are making these 
great exertions, we can do nothing else; we can neither use 
the brain and think, or study, or calculate, nor can the 
muscles perform any other labor. 

139. As much food, then, as the system needs and the 
stomach can digest, gives a man comfort, strength, and ability 
to apply his powers to business. It enables him to use his 
brain, and his muscles, and his bones — to work with his 
hands, his feet, and his mind. But all excess of food beyond 
this, every mouthful more than is needed or easily dissolved, 
gives weakness, instead of strength, for business. It is a tax 
upon the vital energies, and a clog upon the motions of the 


DIGESTION AND FOOD. 


67 


body and the actions of the mind. We see this, in a remark- 
aide degree, in the glutton, who, after his dinner, can do 
nothing but digest. He can neither work nor think, because 
all the power of body and brain are concentrated in the 
stomach. There are not many who indulge theii appetite to 
this extent, and suffer so much in consequence. But there 
are many who err in a lesser degree. They are not gor¬ 
mandizers, yet they eat too much, and suffer in weakness 
precisely in the ratio of their error. 

140. It has been before shown (§ 41, p. 26) that rapid 
eaters consume more than they need or can digest. Yet many 
eat rapidly, in order to gain in time. They imagine that 
twenty minutes or half an hour, spent at their table, is a 
waste of many minutes, which they might employ in business 
or labor. They masticate little, and swallow morsel after 
morsel in quick succession, and soon their stomachs are 
filled; and then they hurry back to their employment, in the 
mistaken confidence that they have gained by this haste, and 
that they shall accomplish so much the more by thus shorten¬ 
ing the time of eating. But they carry with them a load that 
consumes a portion of their strength, which they might other¬ 
wise have devoted to their labor. The farmer and the 
mechanic — the merchant and the student — every man who 
wishes to accomplish the most by the use of his physical or 
his mental powers — will effect his purposes the most suc¬ 
cessfully, by eating slowly and cautiously, and giving ample 
time to the table. It therefore is bad economy to hasten at 
our meals. 

141. A merchant of Boston told me that, when formerly 
engaged in business, he has often walked a quarter of a mile, 
and eaten his dinner, and returned to his counting-room in 
fifteen minutes; and was then pleased that he lost so little 
time. While at table, he swallowed his food as fast as pos¬ 
sible, giving insufficient time to his mouth for mastication, 
and as little to his stomach to mix the food with the gastric 
juice; and yet he ate too much, and was oppressed after¬ 
wards He gained in time, but he lost in energy and in 


68 


PRACTICAL PHYSIOLOGY. 


power of attending to his affairs. In the afternoon he was 
somewhat heavy — his brain was not clear — he was indis¬ 
posed to look into his accounts, or to talk with his customers 
upon matters of business; and he accomplished much less 
during the rest of the day, than he might have done if he 
had allowed himself sufficient time for his dinner. This was 
the first result; the second and remoter result is painful 
dyspepsia, which now, after years of error, weighs heavily 
upon him. 

142. It is common to notice this error at hotels, where 
strangers gather. Travellers seem to be often compelled, 
by the impatience of the coach or the railroad car, to 
swallow their hasty meal with all possible speed; and, unfor¬ 
tunately, they too often continue the habit when the apparent 
necessity ceases. For we find the same hurry at meals in 
the steamboats, and at public tables in the cities. In steam¬ 
boats particularly, where the passengers, from morning till 
night, have nothing to do but to eat, there is commonly man¬ 
ifested an eager haste in swallowing food, as if all the 
minutes spent at the table were lost, or worse than lost, and 
the company were resolved to get away from it as soon as 
possible. 


CHAPTER XV. 

Appetite allowed to accompany the Duty of Eating. — Unwise to eat 
for this alone. — We eat too much for Appetite alone, and make 
this the Means of Hospitality and social Enjoyment. — Children’s 
Appetites pampered. — All Indulgence of mere Appetite followed 
by Suffering. 

143. It is one of the proofs of the benevolence, as well as 
the wisdom, of the generous Creator, that whatever duty is 
required of us by the necessities of our nature, is also made 
pleasant in the performance. Food is made necessary for 
the support of the body, and appetite is given to make the 
taking of that food a source of great pleasure. Here are 



DIGESTION AND FOOD. 


69 


two principles to be noticed and observed : 1st, that we 
are commanded to eat as much food, and of such quality, as 
the stomach can easily convert into the material for the 
blood, and the system requires for its nourishment; 2d, that 
this food may be so selected and compounded, and cooked 
in such a manner, as to be agreeable to the palate. We are 
not only allowed by the law of our being to enjoy the pleas¬ 
ures of the table, but there are encouragements and induce¬ 
ments held out for us to obtain this enjoyment, whenever it 
is consistent with the first duty. 

144. But it is plain that this pleasure of the appetite is 
merely the accompaniment , not the main end , of eating, and 
should, therefore, never be the motive for this act. To select 
our food, not according to its nutritive power, or its digesti¬ 
bility, but according to its acceptableness to the palate,— to 
eat when the body does not require nourishment, or, after 
we have taken sufficient for this purpose, to eat some more 
for the indulgence of the pleasure, — these are manifest per¬ 
versions of the duty required of us, and abuses of a privi¬ 
lege granted to us. It would seem a very foolish thing in a 
shipmaster to load his vessel, not with the freight that it 
can carry best, or which is wanted at the port of desti¬ 
nation, but with that which is the pleasantest to load; or if, 
for the same reason, he should, when his ship is filled, still 
crowd in more than the vessel can carry, or the market 
will justify. 

145. This would be foolish indeed, but not more so than 
for a man to select and measure his food without regard to 
the wants of nutrition in his body, or to the power of the 
digestive organs to convert it into the material of the blood, 
but according to the pleasure of its passage from the table to 
the stomach. In the case of the ship, when the unfitting or 
excessive cargo is crowded into the hold, it can be taken out, 
and the vessel spared the danger of sinking, and the mer¬ 
chant saved the loss on merchandise sent to a wrong desti¬ 
nation, and no damage need be sustained but the labor of 
loading and unloading. But, when the food is once in the 


70 


PRACTICAL PHYSIOLOGY. 


stomach, there is, generally, no return; whatever is once 
there, although out of place, must remain or go onward at 
the cost of comfort and strength of this organ, and of the 
whole body. 

146. It would seem that these principles must be plain to 
every one, so that no man would overload or improperly load 
his stomach, any more than he would his ship or his wagon, 
for so slight a motive as the pleasure of the first step in the 
work. Yet this error is among the most common in society. 
It seems to be forgotten that the appetite and the mouth are 
made to subserve digestion and nutrition; and the world eats 
as if the whole digestive system were the mere servant of the 
palate, and made to carry whatever burden this may impose 
upon it. 

147. The pleasures of good eating occupy many men’s 
thoughts; they are the subject of much conversation; they 
have had their praises sung by many a poet; while the fitness 
of food for the purposes of life is scarcely thought of, and still 
more unfrequently discussed. Few there are who do not 
understand the flavor of the various articles of diet, or the 
pleasantness or unpleasantness of the different methods of 
cookery. Yet the nutritive power, or digestibility of these 
articles, and the effects of cookery upon their qualities, are 
almost unknown to the world. 

148. With this ignorance of the true purposes and conse¬ 
quences of eating, and with the too common disregard of 
the wants of the body and the powers of the stomach, it is 
not surprising that appetite should very frequently be the 
governing law in this matter, and that men should eat for 
pleasure, rather than for nourishment and sti jngth; and such 
is the fact. The stomach is made the receptacle of what¬ 
ever the capricious and ungoverned appetite selects and 
sends to it. Our tables are spread, not only wdih substan¬ 
tial that nourish the body, but with delicacies that tempt 
the palate. We eat not only enough to support the body, but 
often we add to this much more for the mere enjoyment of 
the act, and we urge our friends to partake of the various 


DIGESTION AND FOOD. 


71 


kinds, not because the food is nutritive, — not because they 
are hungry and need it, — but on account of the inviting flavor 
of the dishes. Our argument to our guests is hot, “ You are 
hungry, and this will strengthen you,” but, “ This is pleas¬ 
ant to the appetite, and you will for a moment enjoy it.” 

149. The appetite is made the means, and the stomach is 
compelled to bear the burden, of much of our enjoyments, 
and of our hospitality. Men manifest their love for their 
friends by offering them delicious food, by inviting, and even 
urging, them to partake of what their systems do not need, 
and their powers of digestion cannot easily bear. And, in 
this earnest and well-intentioned endeavor to make their 
hearts glad, they give their stomachs pain and disease. There 
is a great proneness among mankind to make many occasions 
of public and private festivity. There is a strong inclina¬ 
tion, when men gather together for enjoyment, in whatever 
way, — whether for dancing, or conversation, or for the cele¬ 
bration of a public and joyful event, — to add to the social 
pleasure the luxuries of good and plentiful eating. And the 
very means they use to signify their present joy, is the source 
of future suffering in a greater or less degree, in proportion to 
their disobedience of the law of nutrition. 

150. With children, the wants of nutrition appear first, 
before all other wants; the appetite for food predominates 
over other desires, and is ever seeking for gratification. This 
seems to be the readiest means of pleasing them; it is there¬ 
fore frequently appealed to by those who wish to give them 
pleasure. Delicacies of many sorts — fruits, cakes, confec¬ 
tionery — are offered them by those kind-hearted but indis¬ 
creet friends, and too often by their parents and nurses, as a 
means of soothing pain or assuaging grief, or even pacifying 
anger, or winning approbation. 

151. Men and women of every age, as well as children, 
generally consider it a proper and harmless privilege to in¬ 
dulge this appetite when delicacies invite, and when oppor¬ 
tunities offer. Some few of them are epicures, and, finding 
daily opportunities, always eat to oppressive fulness. But 


72 


PRACTICAL PHYSIOLOGY. 


most of them are generally more moderate in their indul¬ 
gence, yet overstep now and then, by adding to the sufficien¬ 
cy of their regular meals another and another portion which 
tempts their taste, or by taking at other times some pleasant 
little refreshment, which chance may throw in their way, but 
which afterwards becomes a source of oppression to their 
organs of digestion. There are others whose habits of eat¬ 
ing are generally in accordance with the natural law, and 
whose daily food is usually no more and no other than their 
nourishment requires. Yet these will, on perhaps rare occa- ** 
sions, meet in parties, or go upon excursions of pleasure, 
which include a feast; and then they give free rein to their 
appetite, and indulge in the pleasures of the table. 

152. All these indulgences of appetite, when for nutrition 
there is no call for food, or when we have already eaten as 
much as we can with ease convert into chyme, must neces¬ 
sarily lay a tax upon the stomach; and, so far as they exceed 
the wants of the body, they do not add to its strength, but, 
on the contrary, they bring upon it weakness. These are 
plainly violations of the law of life, and are inevitably fol¬ 
lowed by the consequences of disobedience. The conse¬ 
quences are not one and the same for all, whatever may be the 
error, but they are measured out in precise proportion to the 
delinquency. The constant epicure suffers more than the 
occasional gourmand, and the frequent gourmand more than 
he who but rarely indulges in eating more than he needs. 
But none escape. All — the least as well as the greatest 
offenders — have greater or less oppression. In some it is 
almost imperceptible; and in others it is almost intolerable. 

It is a singular perversion of the digestive organs, to compel 
them to receive and to attempt to digest food of such quan¬ 
tities as are not needed for nutrition, and of such qualities 
as nature never intended they should convert into chyle for 
the blood. But this apparatus is sometimes perverted to 
stranger and more dangerous purposes than even these. 
Children and men put into their mouths, and masticate, and 
often swallow, some materials which cannot be dissolved in 


DIGESTION AND FOOD. 


73 


the stomach, and from which no nutriment can be extracted. 
From diseased appetite or perverse habits, some boys and 
girls chew India-rubber, pitch, or slate-pencils. I once found 
almost an entire school in the habit of chewing one or 
another of these things. These unnatural things disturb and 
disorder the stomach, and often result in very serious disease 
Some of the most inveterate and distressing cases of indiges¬ 
tion which I have seen, arose from such beginnings as these. 

153. Although we are not allowed to exceed the wants of 
the system or the digestive power, in the least degree, with¬ 
out suffering, yet the opposite error is equally contrary to 
the law of life. Nature is very exact in her demands, as 
well as in her concessions. She will not give health and 
strength for one morsel more than her requirements; nor 
will she relax and give unalloyed comfort and full vigor for 
one morsel less. A definite quantity of nutriment, varied 
to suit the varieties of persons, will nourish and strengthen, 
and entirely meet the wants of each individual. Any smaller 
quantity will give less strength and power of labor of body 
and of mind. The strength of the laborer will fall short of 
its fulness, in proportion to the diminution of his nourish¬ 
ment. Whether this diminution be in the quantity or the 
quality of his food, the result of weakness is the same. 
Whether it be from a short allowance of good food, or the 
innutritious quality or the indigestible nature of bad food,— 
which cannot be converted into chyme or chyle, — or from 
whatever cause, less than the ordinary and sufficient quan¬ 
tity of nutriment is sent from the digestive organs to the 
blood-vessels, the final end is that the frame is not fully nour¬ 
ished or strengthened. Poor meats, thin soups, and innu¬ 
tritious roots, are insufficient for the laboring man; and it is 
bad economy to endeavor to support him on such diet. 

154. Even students, and men engaged in sedentary employ¬ 
ments, cannot maintain their full health, and their energy and 
clearness of brain, upon a diet lower than their natural re¬ 
quirements. Some students in college, for the sake of econ¬ 
omy, endeavor to live upon very little and cheap food. But 
7 


74 


PRACTICAL PHYSIOLOGY. 


they suffer in consequence, and are unable to pursue their 
studies with their original vigor. One of my fellow-students 
endeavored to support his body with eight ounces of bread 
a day, without other vegetable food or meat. He followed 
this plan four weeks, and in that time suffered from head¬ 
ache, nervousness, general debility, and indisposition to ap¬ 
ply his mind to his books. But on returning to the usual 
but moderate diet of other students, he regained his usual 
health and mental vigor. 


CHAPTER XVI. 

Greater Flow of Blood and of nervous Energy to Parts and Organs 
in Motion, and to Stomach during Digestion. — Action in other 
Parts interferes with Digestion. — Mental Labor has the same Ef¬ 
fect. — Rest requisite after Eating, and before Eating. — Gymnas¬ 
tic Exercises at Cambridge. 

155. When any one organ or portion of the body is in 
action, more blood is sent to it, through the arteries, to meet 
the changes, and supply its waste, and support its powers ; 
at the same time, there is more nervous energy sent to this 
part, to quicken its activity. When this unusual flow of 
blood and nervous influence is toward one spot, there must 
be proportionably less sent to all the other parts, and conse¬ 
quently the rest of the body must be comparatively languid 
or inactive. No two portions or organs can, then, be kept 
in the fullest and most vigorous action at the same time, for the 
extraordinary flow of blood, and of quickening nervous 
power, cannot be supplied to both or all at once. 

156. This is particularly applicable to digestion of food 
jm the stomach. While this is going on, the preponderance 
of blood is towards this organ, to sustain this new action, 
and furnish the materials of the gastric juice ; consequently, 
there must be a smaller proportion of blood in the other 
parts of the body. Upon the same principle, the nervous 



DIGESTION AND FOOD. 


75 


influence flows in a larger proportion to the stomach, — the 
seat of action, — and in a less proportion to the rest of the 
frame. It is plain, therefore, that while digestion is going 
on, or until the gastric juice is prepared sufficiently for the 
digestion, the other parts have a smaller supply of blood to 
sustain their actions, and less nervous power to quicken 
their life; they must, consequently, be comparatively lan¬ 
guid, and should be suffered to rest. 

157. jFull, vigorous action cannot , then , he well sustained 
in two parts of the body at the same time. If this be at¬ 
tempted, one or the other must fail, or both be imperfect. 
In order to insure perfect digestion, the stomach must be 
allowed to do its perfect work, and no other organ must 
make active exertions while this is going on. We should, 
therefore, let both the body and the mind rest for a short 
period after each meal. It is a custom in Spain to take a 
short nap after dinner. This is often quoted as a proof of 
Spanish indolence. It is no indication of indolence. It is 
rather a mark of wisdom ; for this leaves the digestive organs 
an opportunity to do their work undisturbed, and to prepare 
for the body that new nutriment which is to give it power 
of action afterwards. 

158. Action of the mind , as well as action of the body , 
interferes with digestion; and the digestive process inter¬ 
feres with mental activity. Immediately after a hearty din¬ 
ner, one is indisposed to think, or thinks but lightly. He is 
averse to study, to business cares, to calculations, and to any 
matter that requires vigorous thought. Ask him then to 
consider a grave subject, or ask a boy, in a similar situation, 
to learn a difficult lesson, and either will be glad to postpone 
the labor until the digestive process is over. If severe men¬ 
tal labor be undertaken, it will not be carried on easily; 
and, if it be carried on at all, it will be at the cost of the 
digestion. Both these operations cannot be performed suc¬ 
cessfully at the same time. Yet it is not necessary that the 
brain be perfectly dormant. A pleasant and light action, 
such as accompanies cheerful conversation, or reading light 
works, does not interfere with this work of the stomach. 


76 


PRACTICAL PHYSIOLOGY. 


159. If any other organ or system be put in violent exer 
cise, or in a state of high excitement, immediately or soon 
after the meal is eaten, the digestion is interrupted, or 
even suspended. A striking experiment was tried by a gen¬ 
tleman in England. He gave to several hounds as much 
food as they could eat, and then put some of them into a 
kennel where they had no opportunity of motion; the others 
were put upon the chase, and kept running in hot pursuit of 
game for an hour or more. At the end of this period, he 
killed some of both classes, and examined their stomachs. 
He found the food in the stomachs of those dogs, which had 
been running, in the same condition as when first swallowed; 

— it had remained unchanged. But in the stomachs of the 
others, which had been at rest, it was digested and converted 
into pulpy chyme, and had gone mostly out of the stomach 
into the alimentary canal. 

160. It may not be necessary that we should sleep, like 
the Spaniard, after our dinner, but it is necessary, for per¬ 
fect digestion of the food, and effectual nutrition of the body, 
that we do not, like the running hounds, engage in violent 
exercise at that time. Indeed, all active labor immediately 
after eating, interferes with digestion, and of course with the 
purposes of the meal; and this interruption must be in pro¬ 
portion to the activity of the motion. If violent exercise 
suspends entirely the work of the stomach, exercise less 
laborious will interfere with it in some degree. Yet abso¬ 
lute rest or sleep is not necessary. Dr. Beaumont says, 
“ Gentle exercise facilitates the digestion of food.” In the 
course of an hour from the meal, the gastric juice is sent into 
the stomach, sufficient for the digestion, and is completely 
mixed with the food. Then we may proceed to active em¬ 
ployment, without fear of disturbing the digestive process. 

161. When any of the organs or limbs have been greatly 
exercised, there come a fatigue in that part which has 
labored, and a lassitude in the whole frame; and then none 
of our powers are disposed to active exertion; all want rest. 
When the fireman’s feet are fatigued with running a long 


DIGESTION AND FOOD. 77 

distance to a fire, he is not ready to take hold of the brakes 
of the engine, and pump with successful vigor. Nor, after 
fatiguing the arms with the engine, is he inclined to make 
equal exertion with the feet in running a race homeward. 

162. Fatigue of the body affects the mental powers in 
the same way. When the laborer has finished a very hard 
day’s work, or when the fireman returns from his violent 
exertions at a fire, he is disinclined to active thought, and, 
perhaps, even to read, and may fall asleep over his book. 
Nor at any time do we readily think upon any serious sub¬ 
ject, or attend to any business that requires grave thought, 
immediately after we have made great and fatiguing exertion. 

163. While any limb or organ is in action, there is a 
greater waste of particles. At the same time, there is a 
greater flow of blood to supply this waste, and of nervous 
power to quicken the action. But, if the action be violent, 
the waste is greater than the new supply, and consequently 
the part is exhausted, and the body feels fatigued. The 
exhaustion of particles and the fatigue remain after the 
action is over. If we are then quiet, the blood and the 
nervous energy still continue to flow in unusual quantity, to 
restore the previous waste, and to revive the diminished life. 
By this means, we rest, and recover lost powers. While the 
brain and the blood-vessels are thus restoring any fatigued 
part, they cannot sustain a vigorous action in another; and 
if we then attempt to exercise the muscles, or stomach, or 
brain, and work, digest, or think, we shall do it but languid¬ 
ly, — probably unsuccessfully, — because the blood and ner¬ 
vous energy which are needed to sustain these actions are 
wanted and used elsewhere. 

164. During the first process of digestion, the stomach 
requires a greater flow of blood and of nervous energy to 
sustain this action. But if these be still required in re¬ 
storing the waste, and the power of other parts, exhausted 
and fatigued by previous exertion, they cannot be given to 
the stomach. If, therefore, when we are much fatigued 
with exertion of the muscles or of the brain, we fill our 

7* 


78 


PRACTICAL PHYSIOLOGY. 


stomachs with food, this organ cannot receive from the 
blood, or from the nervous system, that aid which is neces¬ 
sary to enable it to digest. The laborer, therefore, should 
not go directly from his hard work, nor the student from his 
severe study, nor the merchant from his oppressive anxieties, 
to the table. But each should allow a short interval of rest, 
and then he is prepared to eat and digest his food. 

165. It is not uncommon for students to devote the hour 
before dinner to their exercise. Schools and academies, and 
even colleges, usually have this hour of leisure to be taken 
from books and devoted to recreation. That there should be 
rest of the brain at this time is well. When the gymnasium 
was established at Harvard University, in 1826, the students 
were invited to go to the playground at twelve, and engage 
in the gymnastic exercises till one o’clock. These were 
very active, and some of them violent, for men and boys of 
their strength, so that, when they left the field for dinner, 
they were generally fatigued, and some were almost ex¬ 
hausted. Those who were most fatigued, ate their dinner 
with less than their usual relish, and felt neither refreshed 
nor comfortable afterward. Their stomachs could not digest 
the meal with the usual ease, and consequently they were 
heavy, and indisposed for study in the afternoon. 


CHAPTER XVII. 

Cheerful Conversation at Meals aids Digestion. — Silent and solitary 
Meals unfavorable to Digestion. — Consequences of Abuse of di¬ 
gestive Organs. 

166. During the time of eating, the body should be seated 
in a comfortable and easy position, and all the organs and 
powers, except the digestive, should be at rest. The 
muscles and the brain should be quiescent. The mental 
and the moral powers should yield, for the time, to the busi¬ 
ness of calm nutrition. The mind should therefore be free 
from the burden of deep reflection, care, and anxiety. None 



DIGESTION AND FOOD. 


79 


of the evil passions — anger and envy — should ever be al¬ 
lowed to come to the table. All great and severe thought, all 
labored discussions, and matters of business, should be ban¬ 
ished thence, and light and cheerful conversation take their 
places. The lively play of the social affections, the pleasant 
intercourse of family and friends, the enlivening flow of wit 
and humor, keep the brain in action, but not in labor 
With these, the blood moves more freely, and the nervous 
energies flow more joyously, and the work of digestion is 
moie readily begun, and more easily carried on, and they 
should ever be present at our meals. 

167. The eating hour is the time to cultivate the social 
nature. This harmonizes well with the lively flow of spirits 
that aids the digestive process. It is better, therefore, not to 
eat alone, nor even in silence. The solemn stillness that 
reigns over the table of some families, the unbroken quiet¬ 
ness which a stern but mistaken discipline imposes upon some 
children, are at variance with the best interests of the time. 
They lay a weight upon the brain, a burden upon the spirit, 
and prevent that quickening which social cheerfulness would 
give to the stomach. 

168. These several steps and conditions of digestion, of 
nutrition, and strengthening, were established by the Creator. 
They are among the very laws of our being, and cannot be 
changed. The only way we can gain the most strength for 
labor of any sort, is by perfect obedience to these laws, and 
fulfilment of these conditions. All failure of this must result 
in loss, and defeat the very purpose for which they are vio¬ 
lated. The loss is immediate in the depreciation of power, 
greater or less, in proportion to the delinquency. The loss 
is also accumulative and remote, because the stomach itself 
loses power to do its ordinary duty when unnatural burdens 
are imposed upon it, or when it is not allowed the requisite 
aid to bear them. 

169. The first consequence of neglect of these laws of 
eating is, an imperfect nutrition, a comparative weakness at 
the time, inability to accomplish, with the brain or the 


80 


PRACTICAL PHYSIOLOGY. 


muscles, what otherwise could have been done; therefore, a 
direct loss of power, and of means of production. But the 
later consequence is more important and lasting. The 
stomach being called upon to digest unmasticated food, or 
more than it can dissolve, is disturbed and wearied with the 
excess of labor, and falters. It struggles, but struggles in 
vain, until it exhausts much of its power in the wearisome 
effort. It then becomes so weak that it cannot digest even 
the common food, which in good health it would have easily 
done, and becomes so irritable as to bear only in pain the 
natural and proper burden. This is dyspepsia , which is the 
common result of improper use of our organs of digestion. 
This is a disease painful to be borne, and difficult to be 
relieved, and often ends only with life. In its first stage, 
the work of digestion is imperfect; and in the second, the 
digestive machine is impaired, and finally destroyed. 


CHAPTER XVIII. 

Animal and Vegetable Food. — Northern Nations carnivorous.— 
Equatorial Nations herbivorous. — Vegetable Diet. — Mixed Diet. 
— Stimulating Food. — Climate and Season affect Diet. — Vegeta¬ 
ble Diet in Torrid Zone. — Mixed Diet in Temperate Zone. 

170. There is a great variety of food. There are many 
kinds that differ widely from each other; and these may be 
prepared, compounded, and cooked in a great variety of 
ways; so that the differences caused by art may be even 
more and greater than the differences of nature. It is im 
portant for us to know which of these afford us the easiest 
and the best nutrition. 

171. The first natural division of food is into that of 
vegetable and animal origin. It is not yet a settled question, 
which of these is best fitted for the nutrition of the human 
body, — which will give to man the greatest strength and 
power of action, — the greatest comfort and most perfect 



DIGESTION AND FOOD. 


81 


health, — the clearest brain and the longest duration of life. 
Some have contended, that man was intended to eat only 
of the fruits and vegetables of the earth; while others main¬ 
tain, with equal confidence, that he should add to these the 
flesh of beasts. But none have thought that he should live 
exclusively upon animal food. 

172. The advocates of both these doctrines find exten¬ 
sive examples in the various nations and the various individ¬ 
uals of mankind. Many nations within the tropics live upon 
vegetable food alone; while some tribes within the arctic 
circles feed almost entirely upon the flesh of animals or 
fish. The inhabitants of the cold regions of the earth 
are generally carnivorous, and the residents of the warm 
countries herbivorous; while those who live in the temperate 
climates are both carnivorous and herbivorous. Here in the 
United States, and in the central regions of Europe, the 
mixed diet is almost universal; and the people are as healthy, 
and have as great a duration of life, as any upon earth. 

173. There are many individuals, in this and in other 
countries, who confine themselves to vegetable diet. They 
believe they enjoy better health, and maintain greater 
strength of body and mind, than those who live upon mixed 
diet. The experiment has not been tried on a sufficiently 
extensive range to determine its value. It has not proved 
a failure, nor has it demonstrated, to the satisfaction of all, 
that flesh is injurious. There are no advocates here for 
the exclusively flesh diet; but the doubt is only between the 
mixed on the one side, and the vegetable food on the other. 

174. It is generally believed , among civilized nations , that 
the mixed diet is the best for man — that this will give him 
the fullest health and the longest life. The organization of 
the human body admits this. The form and arrangement of 
the teeth (§ 10, p. 12) allow him to cut and masticate both 
the animal and the vegetable food; and the structure of the 
stomach and alimentary canal enables man to digest both; 
so that he can use either exclusively, as the Esquimaux eat 
flesh, and the Hindoos eat rice; or he can use both, as most 


82 


PRACTICAL PHYSIOLOGY. 


of the inhabitants of the temperate climates eat bread and 
meat together. Admitting, then, this question to rest for 
the present, and that we are to use the mixed diet as we 
have done, still, there are other and subordinate questions, 
with regard to each individual, to be answered, before we 
can determine what we shall eat. 

175. The various kinds of food differ as to their effect 
upon the animal body. One kind, including most meats, is 
stimulating, and gives a greater elasticity of life. This 
would excite some fever, when there is a feverish tendency. 
Another kind, including fish, eggs, vegetables, grain, and 
fruits, has no stimulating power. These would not quicken 
the pulse nor excite fever. The spices, and food in which 
they are mixed, are warm and heating. Many of the vegeta¬ 
bles are cooling. These differences must be known, before 
the fitness of the various kinds to the condition of man can 
be determined. 

176. Climate and season affect the human body , and its 
wants and power of digestion , very materially. We want a 
somewhat different diet in the warm and in the cold seasons. 
We eat more meat and stimulating food in the winter, and 
more vegetable and cooling food in the summer. The tribes 
about the arctic circle live almost exclusively upon animal 
food. They will eat meat in great quantities without either 
bread or vegetables to accompany it. They devour fish 
of the coarsest kinds, — whale, porpoises, &c.,— such as we 
think unfit for our nutrition, and impossible to be digested 
in our stomachs. They will drink whale oil with as much 
apparent relish as we drink milk or water. The voyagers 
to these northern regions, while they are passing the winter 
among these people, fall into their habits of eating: they find 
both that they need and that their stomachs can digest this 
coarse and stimulating food, which would have been oppres¬ 
sive and indigestible at home in a temperate climate. 

177. On the contrary, the inhabitants of the tropical re¬ 
gions live very much, and some nations entirely, upon vege¬ 
table food. Some of these nations never eat meat, and most 


DIGESTION AND FOOD. 


83 


of them eat it rarely ; certainly, they make it a secondary 
article of their diet. But in the temperate climates, in the 
middle regions between the extremely hot and the extremely 
cold, a mixed diet is generally, and almost universally, adopted. 
Even here, the proportions of the meat and the vegetable 
vary with the climate. In the warmer countries, — in the 
south of Europe, and as we approach the tropics, — the vege¬ 
table predominates; and among the northern nations, to¬ 
ward the frigid zone, the meat is the main dependence for 
nourishment. This is in obedience to the general law of 
life, that the body needs, and the stomach can bear, a more 
highly stimulating food, when and where the atmosphere is 
cold, than when and where it is warm. 


CHAPTER XIX. 

Temperaments. — Lymphatic. — Nervous. — Sanguine. — Bilious. 
— Difference of the Excitable and the Inexcitable.— Diet to be 
regulated according to Temperament. 

178. There are differences of individuals that should re¬ 
quire corresponding differences of diet . It is plain, even to 
the most careless observer, that men are not all alike. One 
is dull, difficult to be moved, and habitually inactive. Anoth¬ 
er is quick, irritable, and easily excited or depressed ; he is 
gratified or disturbed with very small matters and is restless 
in his disposition and habits. These differences arise from 
the physical condition of the individuals, from their ori¬ 
ginal organization, and constitute, in part, what are called the 
various temperaments of men. Physiologists have divided 
mankind into several classes, as to temperaments, according 
to the predominant traits in their constitution. Some have 
made four of these classes, calling them the lymphatic , ner¬ 
vous , sanguine , and bilious temperaments. Others have 
made more classes. But however few or many any physiolo- 



84 


PRACTICAL PHYSIOLOGY - . 


gist has adopted, there have been combinations ana mixtures 
of traits, forming other and intermediate classes, such as the 
nervous-bilious , the nervous-sanguine , &.C. 

179. In persons of lymphatic temperament, the form is 
generally full and round, fat, or tending to fatness; the 
skin is soft and rather full ; and the flesh is loose, and some¬ 
what flabby; the muscles are weak, and the whole body is 
inactive. There is an indisposition to exertion, either of 
body or of mind; the temper is calm and inexcitable, 
and the passions are not easily roused. Men of this temper¬ 
ament are not easily excited, and can bear much stimulation. 
They should therefore have food of a stimulating nature, — 
such as beef, mutton, coffee, — which tend to counteract their 
indolent disposition. On the contrary, their natural indo¬ 
lence is increased by a weak and unstimulating diet. Fish, 
oysters, eggs, and most of the vegetable roots, would aggra¬ 
vate the peculiarities of this temperament. 

180. The nervous temperament is marked by predomi¬ 
nance of the brain and nerves, and by great nervous excita¬ 
bility. Men of this class are easily excited, and as easily 
depressed. They are susceptible of high pleasures and 
great distress. They are very sensitive to external influence, 
both upon their body and upon their mind. A strong stimu¬ 
lating diet would increase these peculiarities; but, to coun¬ 
teract them, a mild and cooling, yet a nutritious diet is 
necessary. 

181. In the sanguine temperament, there is greater devel¬ 
opment and activity of the apparatus for the circulation of 
the blood, and nutrition of the heart and blood-vessels. All 
the physical powers are strong, elastic, and easily excited. 
Men of this class are bold and resolute; they are ready to 
act, but not persevering; they soon become weary, especially 
if difficulties present themselves. Their bodily faculties 
predominate over their mental, and they are men of action 
rather than of thought. They are not scholars, nor the most 
cautious men of business. The boys are foremost at play, 
but not in school. These cannot bear excitements or stimu- 

8 * 


DIGESTION AND FOOD. 


85 


Jants, without danger of disease. Stimulating food or drinks 
create an unnatural activity of the heart and blood-vessels, 
and are therefore injurious to them. 

182. In the bilious temperament, the skin is brown, and 
inclining to yellow; the hair is usually dark; the form is 
moderately full, but not fat; the limbs are not gracefully 
rounded, but the muscles are well developed and very strong. 
Men of this class are not very quick in mind or body. 
They are calm and placid — not irritable in temper. They 
have great boldness of purpose, energy in action, and perse¬ 
verance in their undertakings. They are men who succeed 
in their course of life, because they are cool and cautious in 
their plans, and indefatigable and persevering in carrying 
them into execution. In the higher and in the lower walks 
of life, they are successful. 

183. Wherever persons of the bilious temperament be¬ 
gin life, they go up higher. There is within them a restless 
energy, that is not content with the present, whatever it may 
be. Napoleon Bonaparte is a remarkable instance of this 
temperament; a friend of mine, who at twenty-two years of 
age was an hostler, and is now owner and commander of one 
of the largest steamboats on the Mississippi, is another; and 
most of those who in the beginning of life were day-labor¬ 
ers, without means or friends, but afterwards are prosperous 
and wealthy, and become the leading men in their towns, 
and the governing men in their respective business associa¬ 
tions, all, or nearly all, belong to this class, and are of the 
bilious temperament. These men neither need, nor are they 
benefited by the stimulating diet of the lymphatic, nor by 
the spare and cautious diet of the nervous and sanguine. 
Their temper and habits of life generally imply a great 
amount of action of body or mind, generally of both, and 
consequently a great expenditure of material; they need, 
therefore, a full and generous diet of nutritious food, to sus¬ 
tain them in their activity. 

184. Without supposing that any one can tell exactly the 
temperament of himself, or of his companions, yet one can 


86 


PRACTICAL PHYSIOLOGY. 


hardly fail to observe a difference among his associates. One 
is active and sprightly; another inactive and dull. One is 
excitable and irritable; another is slow, calm, and placid 
One is hasty and impatient, quick to receive new ideas, oi 
eager to engage in new plans; another is slow of under¬ 
standing, and hesitates about new propositions. These dif¬ 
ferences are very perceptible, both in men and women. It is 
easy to see, among children at school, how much quicker one 
is than another in learning his lessons, and how much more 
impetuous and active at his play. He has not necessarily 
greater talent for learning, nor more fondness for amusement 
than the other, who is more patient and slow at his books, 
and less hasty and boisterous on the playground; but his 
talents and his feelings are all more active. He understands 
his lessons in school more readily, but he is not in the end a 
better scholar; he is more ready in his games of sport, but 
he does not play with more skill. He requires a smaller in¬ 
ducement to begin a task in the school-room, or a game on 
the playground; but he does not persevere so faithfully to 
the end, as the duller and slower boy. 

185. These are differently affected by outward circum¬ 
stances, by affairs of life, by the treatment of others, by grat¬ 
ifications or disappointments. They are as variously affected 
by the matters which they eat or drink. It is well known, 
that one man can drink large quantities of strong spirit 
without being visibly affected, while another can hardly take 
a small portion of wine without being intoxicated. A sim¬ 
ilar difference follows the use of stimulating and unstimulat¬ 
ing food. What is beneficial to one is injurious to another. 
The sanguine and the ardent need a cooling diet. The cool 
and dull want meat, and other exciting food. The quick 
and irritable should live upon bread, vegetables, fish, and 
such other matters as will not excite them. If they thus 
regulate their diet, according to the peculiarities of their 
constitution, they will be better able to control themselves. 
If they disregard these, and eat otherwise, they will give 
strength to those peculiarities already too strong, and the 


DIGESTION AND FOOD. 


87 


lymphatic will become more sluggish, and the excitable will 
have too high degree of action, and run on life too rapidly ; 
and thus both will enjoy less health, and accomplish less, 
than if they lived faithful to the necessities of their consti¬ 
tution. 


CHAPTER XX. 

Difference of Constitution in Childhood and old Age.— Food to be 
varied accordingly. — The Active want more stimulating Diet than 
the Inactive. — When Habits are changed, Food must change. 

186. There is a difference of excitability in the differ¬ 
ent periods of life, which should be supported by a corre¬ 
sponding difference in the quality of the food. In childhood, 
all the powers of life are more active, the blood flows more 
rapidly, the nervous system is more irritable, and the muscles 
more easily stimulated to action; the feelings and passions, 
and all the motions of life, more readily quickened; but there 
is less power of endurance, and the energies are sooner ex¬ 
hausted, than in maturer life. In old age, all the powers and 
systems are in the very opposite condition. There is a slug¬ 
gishness in all the motions, and an inactivity in the limbs: 
and the feelings, the passions, are slow to rise. 

187. There is a wide difference between these conditions 
of life; and, if we should attempt to support them with food 
of the same quality, we should fail of giving each its true 
life and strength. It is plain that the elastic period require- 
a mild and soothing diet, while the inactive period . 
more stimulating food. Children then want milk, bread, 
mostly vegetable food ; and, if they add meat to this, it shorn 
be of the milder kinds, such as fish and fowl, rather than be 
and mutton. But old men need more meat, and that of th* 
most stimulating and nutritious kinds. 

188. The habits of the individual have an important bear¬ 
ing upon the quality of food . Those can bear the greatest 



88 


PRACTICAL PHYSIOLOGY. 


stimulation who have the greatest activity, and whose exer 
cise opens the freest outlet for their nervous energies. On 
the other hand, the habitually indolent and inactive, whose 
nervous energies are not freely expended, do not bear stimu¬ 
lation easily, because they have less outlet for the quickened 
flow of vitality. The laborious and the active should eat 
more stimulating food than the sedentary and the idle. 
Farmers, sailors, masons, carpenters, and out-of-door labor¬ 
ers, want more meat; while students, tailors, shoemakers, 
and house-employed women, want more bread. The former 
thrive best upon beef, mutton, and bread ; while the others, 
when they add meat to their vegetable food, do well with 
chickens, fowl, turkeys, and fish. 

189. Disorders of the stomach arise from neglect of this 
caution. While men are engaged in hard labor abroad 
they have good appetite and vigorous digestion, and very 
properly eat stimulating food; but if they leave their la¬ 
borious occupations, and become jewellers, shoemakers, 
scholars, or merchants, or engage in any light employment, 
their lives, from being the most laborious and active, become 
quiet and often sedentary. They have less change in their 
vital particles, and, of course^ less nutritive want and di¬ 
gestive power. 

190. If, now, these men do not change their diet with 
their habits of exercise, their digestive powers begin to falter, 
and tnen they feel oppressed after eating. They eat with less 
satisfaction, and do not have the sensations of ease and 
comfort after their meals. They are dull, and disinclined 
to go to their usual employments, or their books, or their 
accounts. 

191. When one exchanges a light for a laborious occupa¬ 
tion, he increases his expenditure of particles, and conse¬ 
quently the demands for nutrition. His stomach gradually 
gains power, and his appetite craves more food to meet the 
new habit of life. One of my fellow-students at Westford, 
in 1822, became dyspeptic and feeble. He had little appe- 


DIGESTION AND FOOD. 


89 


tite, and digested his small portions of food with difficulty. 
He left his studies, and went, as a common sailor, to South 
America. At first, he performed little of the light labor of 
the ship, and ate sparingly, as he had on land; but his 
strength of body and power of digestion increased, and, after 
a few months, he was able to do a sailor’s work, and eat a 
sailor’s allowance. He ate the heavy and stimulating food 
of the ship, — the salt meat and hard bread, — with good 
relish and good digestion, and felt no oppression afterward. 


CHAPTER XXI. 

Digestibility and Nutritiousness of Food not identical. — Food easily 
digested not always best for Invalids. — Condiments excite and 
exhaust.— Sensibility of Stomach. — Alcohol and Wines exhaust 
still more. — No single Rule of Diet to govern all Men. 

192. There are two things to be considered in regard to 
all kinds of food; these are, I st, the digestibility — the ease 
or the difficulty of being converted, by the stomach and its 
gastric juice, into chyle ; and, 2d, the quantity of nutriment 
contained in them. And these are not necessarily one and 
the same. One article of diet may be very easily digested, 
but contain very little nutriment. On the other hand, some 
articles are highly nutritious, yet are very difficult to be 
digested. Perhaps no food contains more of the nutritive 
principle than oil, yet few kinds require longer time to be 
converted into chyme. 

193. That food which is most easily digested is not 
always the most suitable for the sick and feeble. Beef and 
mutton are much more readily changed by the action of the 
stomach than gruel. But they are also much more stimulat¬ 
ing to the system ; and, if eaten by the sick and the convales¬ 
cent, they might excite fever, perhaps a return of the disease. 
But gruel, and bread, which may require a longer time and 
a greater labor of the stomach to digest them, do not excite 



90 


PRACTICAL PHYSIOLOGY. 


the circulation of the blood, nor produce fever. Dangerous 
and even fatal consequences sometimes ensue from a neglect 
of this distinction. 

194. When we rub the skin with pepper, mustard, or 
spirit, it creates irritation; the veins and arteries enlarge; 
the blood flows to the place in unusual abundance; there is 
an increased heat in the spot, and the surface is red; there 
are greater action and quicker life; but these effects soon 
cease; and then the skin is pale, the circulation is more 
languid, and the life of the part is more dormant, as unusual 
action of the muscles leaves fatigue behind. These are the 
natural effects of stimulation : first, increased activity; and 
next, increased languor; for all unnatural excitement of the 
natural actions of the living system is followed by a corre¬ 
sponding depression. 

195. The same takes place in the stomach from the use 
of all condiments, such as spices, pepper, mustard, with our 
food. The stomach is stimulated, the circulation of blood 
in its walls is quickened, the gastric juice flows more readily, 
and digestion begins more promptly. But soon this unnatu¬ 
ral activity ceases; and then it falls below its natural stand¬ 
ard, and digestion is finally retarded. This is the effect of 
once using the stimulating condiments; but, if this use be 
continued and often repeated, the power of the stomach, 
from frequent excitement and fatigue, becomes somewhat 
worn, and the organ is permanently enfeebled. To a healthy 
stomach, then, condiments and stimulants, are not only 
unnecessary, but injurious. They give no strength; they 
only quicken the action and expenditure of power already 
existing. 

196. These enfeebling effects follow the stimulation of 
wines and spirits even more than that of spices. Alcohol is 
more speedy in its action, both of excitement and exhaustion. 
Dr. Beaumont saw that St. Martin’s stomach was reddened 
after drinking spirit, and sometimes the covering of the inner 
coat peeled off, and left spots of canker upon the surface. 
The remote result of this drinking is more severe and dan- 


DIGESTION AND FOOD. 


91 


gerous than that of condiments. The stomach gradually 
loses its power, until it becomes incurably dyspeptic, and is 
unable to digest the ordinary food. 

197. The use of all stimulants, both of spices and alcohol 
at first sharpens and then destroys the natural sensibility of 
the tongue and mouth. The healthy appetite of those who 
are unused to stimulants is simple, and wants simple things. 
They have a refined taste, and nice discrimination of the 
different flavor of various kinds of food, and a keen relish 
for what they eat, although it is neither prepared with spice, 
nor accompanied with spirits or wine. But those who are 
accustomed to highly-seasoned dishes are not satisfied with¬ 
out them. All simple dishes are insipid. Their taste is so 
blunted that these do not excite it. And, in the old and 
habitual drunkard, this sensibility is so deadened that nothing 
short of a very active or even pungent stimulant will reach 
and satisfy it. 

198. A friend of mine, who had drunk tea and coffee, 
and occasionally wine, and habitually eaten spices, suddenly 
ceased to use them, and drank only milk and water, and ate 
no other condiment than salt with his food. After eight 
months’ practice of his simple diet, the sensibility of his 
tongue became so exalted, and he gained so nice a discrimi¬ 
nation of taste, that he could distinguish and enjoy the vari¬ 
ous flavor of water from different wells, as readily as he had 
distinguished between the various kinds of wine, tea, and 
coffee. The enjoyment of the mere taste and appetite is not 
in proportion to the stimulating power of what we eat and 
drink, but in the ratio of the quickness of the sensibility. 
And the water-drinker, while in the mere act of drinking, 
enjoys his pure water more than the wine-drinker does his 
wines, or the spirit-drinker his stronger and more stimulat¬ 
ing drinks. “ Happy are the young and healthy,” says the 
shrewd Dr. Kitchener, “ who are wise enough to be con¬ 
vinced that water is the best drink, and salt the best sauce.” 

199. From this examination of the structure and uses 
of the digestive organs, and of their purposes, powers, and 


92 


PRACTICAL PHYSIOLOGY. 


liabilities, we learn that the stomach performs some of the 
most delicate operations, and effects some of the most won¬ 
derful changes, in nature; and that it requires the aid of 
the intelligent hand to supply its wants, and fit the sup¬ 
plies to its necessities. There is no human instinct to be 
our unerring guide, and to direct us what and how much 
we shall eat or drink. The living machinery within, and 
the dead material without our bodies, are prepared for our 
use; and the law of nature is declared to us for our govern¬ 
ment. This we are required to read and to understand, 
before we can perform our part in the sustenance of our 
frames. 

200. This is not a law of appetite, that directs us always 
to eat when we are hungry, and take such kinds of food, 
and as much of it, as the palate craves. Nor is it a law of 
convenience, that allows such food as chance or caprice may 
place before us. But nature has established for every 
man a law which must govern his nutrition. This law is 
founded upon the structure of his digestive organs, the wants 
of his frame, his temperament, his age, and his habits of 
exercise. Every individual must understand these general 
principles, which have been described in this book, and, 
applying them to himself and his circumstances, he must 
determine what food, and how much, will meet the necessi¬ 
ties of his own body. 

201. In this matter, as there are great varieties of men and 
of external circumstances, so there is no one rule of diet 
that will apply to all mankind. All the differences of men 
must be supplied with corresponding differences of nutriment. 
Those codes of diet which are laid down for the government 
of all men, of every variety of temperament, and habit, and 
location, and which attempt to sustain all men with the same 
aliment, are absurd, and fail; for every man, or every class of 
men, have their peculiar powers, and their peculiar wants ; 
and if they disregard these, and endeavor to support life by 
any other rule, they will not fully accomplish the purpose of 
eating. 


CIRCULATION OF THE BLOOD. 


93 


PART II. 

CIRCULATION OF THE BLOOD AND NUTRITION. 


CHAPTER i. 

Apparatus of Circulation. — Heart. — Structure and Divisions. — 

Valves.—Arteries. — Aorta. — Subclavian, carotid, facial arteries. 

— Branches in the lower limbs. 

202. The chyle, or the nutritious part of the digested 
food, is carried from the digestive organs, in the abdomen, 
through the absorbent mouths, and the lacteal tubes, and 
great lacteal duct, to the great veins near the heart. There 
it is mixed with, and becomes a part of, the blood. This 
blood is to undergo certain changes in the lungs, and then 
it is to be distributed to all the parts of the body. 

203. The apparatus for this distribution or circulation of 
the blood consists of the heart , or central organ of motion; 
the arteries , which carry all the blood out of the heart to 
the lungs and to the various parts of the body; the capillary 
vessels , in which nutrition takes place; and the veins, which 
carry the blood back to the heart. 

204. The heart (Fig. VII.) is a hollow , muscular organ , or 
bag, composed of fibrous substance, like lean meat. It is 
capable of contraction and expansion, like the muscular coat 
of the stomach. When it contracts it diminishes its internal 
cavity, and presses out the fluid contents or blood that is 
within it. When it relaxes,its cavity is enlarged and allows 
other fluid or blood to flow into it. 

205. The heart is placed in the centre of the chest, be¬ 
tween the two lungs, (Fig. V. c.) Its larger end is upward, 



94 


PRACTICAL PHYSIOLOGY. 


and behind the breast-bone. The smaller end or apex is 
downward, and turned toward the left. When the heart 
contracts, to send the blood out, the apex is thrown forward 
and strikes against the ribs of the left side, near the breast¬ 
bone, where the beating is very easily felt. 


Fig. VII. Heart. 



a , Right auricle. 

b, Left auricle. 

c, Right ventricle. 

d, Left ventricle. 

e, Great artery carrying the 
blood, from the left ventricle to 
the body. 


f \ Artery carrying the blood 
from the right ventricle to the 
lungs. 

ff, h, Great veins carrying the 
blood from the body to the 
heart. 


206. The internal cavity of the heart is divided by a par¬ 
tition wall of flesh (Fig. VIII. c) into two apartments, 
one on the right, and one on the left. This separation of 
the two sides of the heart is complete. There is no passage 
way through this wall, and consequently no direct communi¬ 
cation between the two apartments. They are sometimes 
described as two hearts united together. 



CIRCULATION OF THE BLOOD. 


95 


Fig. VIII. Heart laid open. View of the four Chambers of 
the Heart. 


a. Left ventricle. 

b. Right ventricle. 

c. Partition wall between the 
two sides. 

d. Right auricle. 

e. Left auricle. 

f g. Partitions between the au¬ 
ricles and ventricles. 

h, h. Great artery leading from 
the left ventricle to the whole 
body. 

i, i. Great vein carrying the 
blood to the heart from the whole 
body. 

k, k. Arteries leading to the 
lungs. 

l, 1. Veins leading from the lungs 

The arrows show the course of the blood through the heart. 

207. Each of the two grand divisions of the heart is again 
divided into two smaller chambers. On the left side, the 
one above (Fig. VIII. e ) is called the left auricle , and the 
one below, (Fig. VIII. a,) the left ventricle. On the right 
side, the chamber above (Fig. VIII. d) is called the right au¬ 
ricle, and the one below, (Fig. VIII. &,) the right ventricle. 
These make four separate chambers in the heart. There is 
no communication between the two auricles, nor any between 
the two ventricles; but there is a passage-way on each side, 
opening from the auricle above to the ventricle below, 
through which the blood passes from the upper to the lower 
chamber. 

208. The blood flows from the auricle to the ventricle, but 
not backward from the ventricle to the auricle. There are 
valves placed at these passage-ways in the heart , which open 
to allow the blood to pass downward, but they close, and 
prevent its passing upward. These valves act on the principle 
of the valve in the common pump box, which opens when the 
water below presses upward, and allows it to pass through; 



96 


PRACTICAL PHYSIOLOGY. 


but it closes again when the water above presses downward, 
and prevents its return to the well. 

209. The heart is the centre of the circulating system. 
It sends all the blood to the whole body through the arteries, 
and receives it back again through the veins. There are two 
sets of these blood vessels, each consisting of arteries and 
veins. One set begins at the heart and extends through the 
whole body. The other set reaches from the heart to the 
lungs. The arteries open from the ventricles or lower cham 
bers of the heart, and carry the blood out. The veins open 
into the auricles or the upper chambers of the heart, and 
carry the blood back. 

210. The arteries are round tubes. They are firm in their 
structure, and retain their cylindrical form when empty. 
They are composed of three coats. The outer coat is dense 
and strong, and is the principal means of resistance to pres¬ 
sure. The middle coat is thick and elastic, and expands 
when the blood flows in, and contracts when it flows out. 
The inner coat is very delicate, and forms a polished surface, 
on which the blood flows easily. The arteries have the same 
structure throughout the body. There is a valve between 
the ventricle and the aorta, which allows the blood to pass 
from the heart into the artery, but not to flow backward 
from the vessel into the heart. 

211. One large artery , called the aorta, leads out from the 
left ventricle upward, (Fig. VII. e, Fig. IX. c, d , e,) and then 
turns downward, (Fig. IX. d.) It passes then along the 
back-bone, through the chest and the abdomen. Great 
branches pass out from this artery to the various parts of the 
body Two branches, called the carotids, (Fig. IX. f, f) 
pass off from the arch and go to the head, one on each side 
of the neck. Two branches, called the subclavians , (Fig. 
IX. g, g,) go to the arms and hands. While passing through 
the chest, the aorta sends branches to the walls of the chest, 
(Fig. IX. h , h.) In the abdomen, the aorta sends the coeliac 
artery to the stomach, the hepatic artery to the liver, the 
renal arteries to the kidneys, &c., and other branches to the 


CIRCULATION OF THE BLOOD. 


97 


various organs in that region. At the lower part of the 
abdomen, the aorta divides (Fig. XI.) into two branches, 

\ lg * e ' e ’) whlch pass through the groins and all the 
limbs below. 

Fig. IX. Aorta and Branches in the Chest. 

a , b , Heart. 

c, Ascending aorta. 

d, Arch of the aorta. 

e, Descending aorta. 

f> f, Carotid arteries 
going to the head. 

g, g, Subclavian arte¬ 
ries going to the arms. 

h, h, Branches going 
to the chest. 

i, i. Branches to the 
right and left lung. 

k, Great artery going 
to the lungs. 


212. The subclavian arteries (Fig. IX. g , g) pass from the 
$rch of the aorta, and, extending under the collar bones and 
through the arm-pits, they reach the arm; at the elbows they 
divide into two main branches. One of these can be felt at 
the wrist, near the root of the thumb. These arteries send 
numberless little branches, which reach all the flesh of the 
arms and hands. 

213. The carotid arteries passing up by the sides of the 
neck, can be felt near the windpipe. At the top of the neck 
they divide into two branches, one of which passes through 
the skull, and is distributed to the brain. The arteries 

9 





98 


PRACTICAL PHYSIOLOGY. 


and branches ramify throughout all the substance of this 
organ. 

The outer branch of the carotid goes to the outside of 
the head and to the face. It sends branches to the forehead, 
the cheeks, the chin, the lips, and the other parts of the face. 
All these organs are thus supplied very abundantly with blood 
by these vessels and their numberless little branches. (Fig. X.) 

Fig. X. Arteries of the Face. 



214. The aorta is divided in the lower part into two great 
branches, (Fig. XI. e, e.) These two branches pass through 
the groins, where they are called inguinal arteries , and thence 
into the thighs, where they are the femoral arteries ; passing 
downward, they divide, and send branches to the flesh of the 
lower limbs, until the legs, the feet, and the toes are sup¬ 
plied with them. 

All these arteries in every part of the body are divided 
and multiplied as they go from the heart, and their num¬ 
berless small branches are distributed into every part of 
the flesh in all the organs and regions of the body. Thus 
all the parts, organs, and textures are supplied with blood 
for their nourishment. 




CIRCULATION OF THE BLOOD. 


99 


Fig. XI. Arteries of the whole Body. 



a, Heart. 

b, c, c , Aorta. 

d, Division of aorta. 

e, e , Inguinal arteries. 


f f Subclavian arteries. 
g, g, Carotids. 
k, h, Branches in the arms. 
i t i, i, Branches in legs and feet. 


















100 


PRACTICAL PHYSIOLOGY. 




CHAPTER II. 

Veins. — Distribution. — Capillaries. — System of general Circula¬ 
tion. — Situation of Arteries and Veins. — Pulmonary Arteries and 
Veins. — Double Circulation. 


Fig. XII. Great Veins. a, Heart. 



b, Ascending vena cava. 

c, c, Subclavian veins. 

d, d, Brachial veins, in the arms. 

e, e, Veins from the outside of the 
head. 

/> /> Veins from the brain. 
g , Descending, or abdominal vena 
cava. 

h } h, Veins from the kidneys. 
i, i, Great branches of veins in the 
groins. 

k, k. Veins from the lower extrem¬ 
ities. 

215. The veins also connect the 
heart with every part of the body. 
Their coats are thinner and softer 
than the arteries. They collapse 
when they are empty. They are 
easily compressed, as can be 
shown by pressing the veins on 
the back of the hand. They 
have valves, which open and allow 
ihe blood to pass toward the 
heart, but close and prevent it 
flowing backward. 

216. One large vein , the vena 
cava , opens into the heart , and 
carries all the blood of the body 

into it. The upper part of this vein, the vena cava ascen- 
dens, extends upward, and sends branches to the head and the 
arms. The lower part, the vena cava descendens , passes 





CIRCULATION OF THE BLOOD. 


101 


through the abdomen, along the side of the aorta, and sends 
branches to the organs of digestion, &,c., and to the lower 
limbs. 

Fig. XIII. Veins of the whole Body. 





a, - Heart. 

b , c, Vena cava. 

d, Division. 

e, e, Inguinal veins. 

g, g, Jugular veins. 

h, h, Branches. 


217. The jugular veins pass upward from the upper great 
vein, through the sides of the neck, to the head. They send 
9 * 













102 


PRACTICAL PHYSIOLOGY. 


branches to the brain within, and to the scalp and the parts 
of the face without the skull. The subclavian veins (Fig. 
XII. c,c) also pass off from the upper great veins. They go 
through the arm-pit, and send numberless branches to the 
arms and hands. The great abdominal cava sends branches 
to the stomach, liver, alimentary canal, kidneys, &,c., and 
finally it is divided (Fig. XII. *, i) into two great veins, which 
with their branches reach all the parts of the lower limbs 
and feet, (Fig. XIII. A, A.) 

218. All these veins, like the arteries, are divided and 
multiplied into branches almost infinitely small and numer¬ 
ous, and thus they reach every part of the animal body, 
(Fig. XIII.) 

219. The arteries are said to begin at the heart with one 
large trunk, the aorta, (Fig. XI. A,) and to end in all the near 
and the remote parts of the body in almost infinite numbers 
of minute tubes. The veins, on the contrary, are said to 
begin in the flesh of all the parts of the body, with tubes 
almost infinitely small and numerous, similar to the termi¬ 
nating arteries, and end in one large trunk, the vena cava, 
at the heart, (Fig. XIII.) These trunks meet at the heart 
with their large trunks, and again they nearly meet through¬ 
out the whole body with their minute extremities. 

220. The capillary system of blood-vessels is placed be¬ 
tween the minute extremities of the arteries and the minute 
ends of the veins. They are called capillaries from their 
hair-like minuteness. They are even smaller than this, for 
they cannot be seen by the eye. They are spread in every 
part and every organ of the body. They form the connect¬ 
ing link between the arteries and the veins, and carry the 
blood from one to the other. 

221. The system of the general circulation of the blood is 
thus composed of the heart , the arteries, the capillaries , and 
the veins. The blood flows out from the ventricle on the left 
side of the heart into the aorta. It passes through this large 
artery into the large branches, and thence into the smaller 
branches, and then through the minute branches into the 


CIRCULATION OF THE BLOOD. 


103 


capillaries, in every part of the body. From these vessels the 
blood flows into the minute extremities of the veins, and 
thence into the larger branches, and finally into the great 
vena cava, which pours the blood into the right auricle of 
the Jieart. 

222. The arteries carry the nutritious blood to support the 
life of the textures. If they are wounded, serious conse¬ 
quences follow, and they are not very readily healed. They 
are therefore placed deeply within the flesh, where they are 
protected from injury. Some of them approach the surface, 
and their pulsations can be felt at the wrist, and at the sides 
of the neck, and on the temple. 

223. The veins carry the impure and wasted blood. They 
suffer less, and are more easily healed, than the arteries when 
injured. Their great trunks are placed near the great arte¬ 
ries, but their branches are situated nearer to, and more of 
them on, the surface, than the arterial branches. They are 
seen on the back of the hand and on the arms; and sometimes 
they enlarge and become very troublesome on the skin of 
the lower limbs. Bleeding is usually performed by opening 
a vein of the arm. 

224. The blood passes out from the left side of the heart 
through the arteries to the body, and returns through the 
veins to the right side of the heart. These two sides are 
separated by an impassable wall, (Fig. VIII. c.) Before 
the blood can reach the left side of the heart, it must pass 
through the lungs. This passage of the blood through the 
lungs constitutes what is called the pulmonary circulation. 

225. The pulmonary artery passes out from the right ven¬ 
tricle, (Fig. VIII. b ,) and divides into two branches, (Fig. 
VIII. &, &,) one of which goes to the right lung, and the 
other to the left lung. These divide, and finally spread their 
minute branches throughout the substance of the lungs. 
The pulmonary veins begin very minute in all the parts of 
the lungs, where the little arteries terminate. These little 
vessels unite again and again, until they form one large vein 


104 


PRACTICAL PHYSIOLOGY. 


in each lung, and then join together and enter the auricle 
on the left side of the heart. 

Fig. XIY. Double Circulation of the Blood. 



The arrows show the course of the blood. 

226. These two sets of vessels constitute what is called the 
double circulation. The blood is in the left auricle, (Fig. 
XIV. a,) and passes thence downward to the left ventricle, 












CIRCULATION OF THE BLOOD. 


105 


(Fig. XIV. b;) thence it Hows through the aorta, (Fig. 
XIV. e,) the large branches of the arteries, (Fig. XIV. d , e,) 
and the minute branches of the arteries in all the parts of 
the body, (Fig. XIV. f, f, f\ f ,) into the capillaries, (Fig. 
XIV. g , g , g , g.) Thence, again, the blood flows into the 
minute veins, (Fig. XIV. h , A, A, 7i,) and through the larger 
veins, (Fig. XIV. *, &,) back to the auricle of the right side 
of the heart, (Fig. XIV. /.) 

This is the general circulation, which carries the blood 
from the left side of the heart through the whole body and 
back to the right side of the heart. 

Next, the blood flows from the right auricle (Fig. XIV. 1) 
to the right ventricle, (Fig. XIV. m.) Thence it passes 
through the great pulmonary artery (Fig. XIV. n ) and the 
great branches of the right and left lungs (Fig. XIV. 0 , 0 ) 
into the minute pulmonary branches, (Fig. XIV. p , p.) 
From these it flows into the minute pulmonary veins, (Fig. 
XIV. q, q , q , < 7 ,) and through the great pulmonary veins 
(Fig. XIV. r, r) into the auricle of the left side of the heart, 
(Fig. XIV. a.) 

This is the pulmonary circulation, which carries the blood 
from the right side of the heart through all the lungs, and 
back to the left side of the heart. 


CHAPTER III. 

Action of the Heart. — Motion of the Blood in the Arteries. — 
Quantity and Flow of Blood. — Rate of Pulsation varies with Cir¬ 
cumstances.— Exercise. — States of Mind and Feelings. Local 
Circulation varies. — We do not govern Circulation, but we maj 
disturb it. 

227. These organs of circulation are admirably contrived 
for their purpose. The muscular texture of the heart 
enables it to contract upon its contents, and expel them with 





106 


PRACTICAL PHYSIOLOGY. 


force sufficient to send them through the arteries to the 
farthest extremity of the frame. The power of the heart is 
not easily measured. Some have supposed that it could 
exert a force equal to that which would be necessary to raise 
several thousand pounds ; while others have estimated it to 
be equal only to a few ounces. 

228. The veins are continually pouring their blood into 
the right auricle, or upper chamber. As soon as this is full, 
it contracts, and empties its contents into the right ventricle, 
or chamber below. In the same manner, when the pulmo¬ 
nary veins fill the left auricle, this presses the blood into the 
chamber below ; and then this lower cavity contracts and 
forces it into the arteries, and through them to the body. 

229. This movement of the blood is always forward. The. 
great vein pours its blood into the right auricle. When this 
upper chamber isjijled, i,t contracts upon its contents, and 

the reflux of the blood into the veins is prevented by the 
valves with which they are furnished; ” but at the same 
time the valve between this cavity and the ventricle below is 
opened, and the blood finds free passage through it. When 
this lower chamber is filled and contracts, the last valve is 
closed, and the fluid has no way of going back to the upper 
chamber; but then the valve between the ventricle and the 
artery opens to allow the blood to enter this tube, and closes 
again as soon as the artery is full; so that the blood cannot 
go back to the heart. In the same manner, the valves on 
the left side of the heart open to allow the blood to pass 
from the veins of the lungs to the left auricle, and from the 
auricle to the lower chamber, and again from this chamber 
to the arteries of the body ; but at each place they close 
when the next cavity is filled, and prevent the return of any 
fluid. 

230. The arteries are capable of expansion and con¬ 
traction. When any thing is forced into them, their coats 
stretch, and their capacity is enlarged; and when their con¬ 
tents are removed, they contract again, and diminish their 
cavity. These have no valves, except that which stands 


CIRCULATION OF THE BLOOD. 


107 


between their great trunk and the heart; and there is 
nothing but this to prevent the backward flow of the blood. 
When the left ventricle beats, and forces its blood into the 
arteries, they expand suddenly to admit the increased quan¬ 
tity. All the arteries in the body expand and beat at very 
nearly the same moment that the heart beats. We can feel 
this beating of the arteries at the wrist, in the temples, the 
sides of the neck, and wherever else they come near the 
surface. Some can perceive it and count their pulsations in 
the brain. 

231. While the heart is pressing the blood into the artery, 
the valve is opened, and the vessel expands. But as soon as 
this pressure ceases, the valve closes, and the artery begins 
to contract and force the contents out and onward through 
itif minute extremities. The blood is then thrown into the 
arteries by a muscular power of contraction, and it is moved 
through these vessels merely by the elastic power of their 
coats. 

232. The left ventricle of the heart will, in a man of av¬ 
erage size, contain about two ounces, or one eighth of a 
pint. Every time the heart beats, this cavity is filled and 
emptied; therefore, two ounces of blood are forced into the 
arteries at every pulsation. In ordinary health, the heart of 
a man beats about seventy-five times in a minute, or a little 
more than once in a second. The quantity of blood in a 
man of average size is estimated to be about twenty-eight 
pounds, or four hundred and forty-eight ounces; and if two 
ounces pass through the heart at every beat, and one hundred 
and fifty ounces every minute, then the whole blood of the 
human body must pass through that organ, and through the 
whole system, once in three minutes. Seventy gallons of 
blood flow through a man’s heart in the course of an hour, 
and sixteen hundred and eighty-eight gallons in the course 
of a day. 

233. This is the usual rate of the circulation; but it varies 
with many circumstances. It is more rapid in most diseases 


108 


PRACTICAL PHYSIOLOGY. 


than in health. The heart beats faster when we are stand¬ 
ing than when we are sitting, and faster when sitting than 
when lying down. The pulsation is more rapid in the morn¬ 
ing than in the evening — in females and in children than 
in males and adults. All exercise increases the force and 
rapidity of the circulation. The rapid and sometimes vio¬ 
lent beating of the heart when we are running, or making 
great exertions, is familiar to every one. 

234. While the body or any of its parts is in motion, the 
changes of the particles go on more rapidly , there is more 
waste, consequently greater need of nutrition, (§ 127, page 
61;) and, to meet this want, the heart quickens its action and 
sends more blood to the frame. There is a great difference 
between the pulse of the active boy and that of the sleeping 
babe. The pulsations of the laborer are strong and hatd ; 
his heart forces the blood vigorously into the arteries, and 
they are distended, full, and feel hard. But the pulse of the 
indolent man is soft and feeble. He takes no exercise; 
the changes of particles are few and slow; there is little waste 
and little need of nutrition; and, consequently, his heart 
sends the blood gently, and oftentimes feebly, through the 
arteries. 

235. The circulation is affected by the states of the mind 
and the feelings . The heart beats with more force and rapid¬ 
ity under mental or emotional excitement; then the arteries 
beat with more firmness, and carry more blood. So when a 
man is excited with anger, or stimulated with hope, or glow¬ 
ing with cheerfulness, or burning with love, his blood flows 
more freely, his system is better nourished, and he is stronger 
and more capable of exertion. The depressing passions 
have the opposite effect of lowering the action of the heart, 
and the force of the circulation. While a man is suffering 
with fear, despair, sorrow, or gloom, his heart beats more 
feebly, and his blood flows more languidly; his body is less 
nourished, his strength is impaired, and he has less power of 

InLnr 


CIRCULATION OF THE BLOOD. 


109 


236 Although the heart sends the blood by the same 
impulse to all the arteries, and all these must then beat, al¬ 
most at the same moment, and in unison, yet the expansion 
and contraction of these blood-vessels are not always the 
same in all parts of the body. Hence the blood may circu¬ 
late with very different force in various parts, and some may 
be supplied very freely while others are but sparingly fed 
with this fluid. Local diseases create a greater local circu¬ 
lation. When one has a felon on his finger, he feels the 
arteries throb sometimes violently in the sides of that fin¬ 
ger, while the beating of the arteries in the other fingers is 
scarcely noticed. Some suffer from cold feet in consequence 
of feeble circulation of blood through those extremities; 
others have headaches from the too great flow of blood to the 
brain. The arteries are more active in the parts that are in 
action. More blood flows to the muscles during the time of 
labor, to the stomach during digestion, and to the brain when 
the mind is actively employed. 

237. This beating of the heart, and this pulsation of the 
arteries, are incessant during life. Day and night, asleep or 
awake, this movement goes on, and every part of "the frame 
receives its supply of blood in due season, without our voli¬ 
tion, and even without our observation. The circulation of 
the blood is not submitted to our care, and we are not respon¬ 
sible for its work, as we are for the work of digestion. Yet, 
though we are not called upon to aid this function, we may 
interfere for evil. We may, by stimulating food or drinks, 
excite the heart too much for health; or, by neglect of 
proper exercise, we may suffer it to become sluggish in its 
motions. 


10 


PRACTICAL PHYSIOLOGY. 


1 10 


CHAPTER IV. 

Object of Eating and Circulation is to nourish the Body. — All Am 
mal Solids and Fluids formed out of the Blood. — Elementary 
Composition of the Blood and Flesh: nearly alike in all the Tex¬ 
tures, but differ in the Proportions of their Elements. — Nutrition 
takes Place in the extreme Vessels, and with unerring Precision. 
Growth and Changes of the Body are at the Cost of the Blood. — 
The Atoms of the Body enjoy but a temporary Life. — When one 
dies, it is removed. — Absorbents. 

238. As the eating and digestion of the food have no 
other object than to supply the wants of the blood, so the 
motions of the heart, and the circulation of the blood, are 
for the sole purpose of supplying the wants of the frame. 
All the growth of the body in childhood and youth, all the 
regaining of flesh after sickness, all increase of flesh at any 
period of life, and all the changes of particles, are supplied 
by the blood. All the textures and secretions of the body, 
various as they are, — the bone, muscle, brain, skin, fat, 
the hair and the nails, the tears, the saliva, and the perspira¬ 
tion,— are all taken from this same storehouse, — from this 
fluid that runs in the blood-vessels of the animal body. 

239. The blood is not flesh, nor does it exhibit any resem¬ 
blance to flesh. It is a homogeneous fluid, the same in all 
the arteries, wherever they may be situated. The blood that 
flows in the brain is of the same nature and composition as 
that which flows in the bones and muscles. The blood is 
not a simple, but a compound fluid. It contains various ele¬ 
ments, and these are the same as those which compose the 
flesh. These simple elements are principally carbon, oxygen, 
hydrogen, and nitrogen. There are others, such as the lime, 
that enters the bones, some phosphorus and sulphur, that are 
found in the hair, the nails, and the brain. These are the 
most common elements in nature. Oxygen and nitrogen 
compose the air; oxygen and hydrogen form water. Carbon 


NUTRITION. 


Ill 


is the principal ingredient in charcoal ; it is the predomi¬ 
nant element in vegetable substances. 

240. All these elements are found in the blood. But they 
are not all found in every texture of the animal body. 
There is no lime in the brain, no sulphur in the muscles, 
and no nitrogen in the fat. Yet, with few exceptions, all the 
various parts and organs are mainly composed of the same 
elementary atoms — carbon, oxygen, hydrogen, and nitro¬ 
gen. The difference of these organs is owing, not to the 
difference of their component elements, but to their different 
combination or arrangement. Combined in one proportion, 
they form tendon; in another, they form muscle; in 
another, potato, tea, coffee. The same elements in various 
proportions, and with some ashes, form flesh, peas, beans, 
oats; and, with some sulphur, they form hair, bone, nails, 
and cheese. The blood is the grand storehouse which sup¬ 
plies all these, in their due proportion, to every organ and 
texture. 

241. The arteries carry this blood to all the parts of the 
body; every point, however minute, receives its supply 
through these tubes. The transformation of the blood into 
flesh, or the separation of such elements from this fluid as 
will compose the kind of flesh that is needed, is done in the 
minute extremities of the arteries, or the capillaries, which 
stand between the arteries and the veins. This work of nu¬ 
trition is done with unerring precision in health; just the 
requisite proportions of carbon, oxygen, and hydrogen, and 
of the other elements, are measured out; and flesh of the 
proper kinds is formed, each in its appropriate place; and 
thus the body increases in size and stature. 

242. All additions to the weight of the body, the growth 
during early years, and the increase of flesh at any time, 
create a certain demand upon the blood for nutrition; but 
the changes of particles, during the whole of life, create 
a much greater demand upon the blood for new atoms. 
After we have reached our fulness of stature, in ordinary 
health, we eat and drink three to four or more pounds of 


112 


PRACTICAL PHYSIOLOGY. 


solid and liquid matter a day ; and yet our weight does not 
usually increase. Even after making this daily addition for 
successive years, we weigh about the same at sixty as we did 
at twenty. This food is digested and converted entirely, or 
in part, into blood; and this blood is converted into flesh, 
muscle, fab, nerve, &c.; and yet these organs and parts 
remain of the same size. 

243. The diligent arteries are almost incessantly adding 
atom after atom to these organs, and yet do not enlarge 
them. The object of their work is, not merely to make new 
atoms of flesh, but to make those which will supply the place 
of other atoms, which have served their purpose in the living 
body, and have been carried away. It has already been 
stated (§ 1, p. 9) that however long the body, as a whole, 
may continue to live, none of its component particles can 
enjoy any considerable duration of life. These particles are 
deposited, by the arteries or the capillaries, in the various 
organs and textures; and then they are endowed with life, 
and the peculiar properties of the part in which they are 
placed. In the muscle, they have the pow'er of contraction, 
and in the brain, the power of feeling and perception; and in 
the bone, they are hard and strong, and apparently in¬ 
sensible. 

244. But in a little while this vitality , this property of 
life , is exhausted, and the atom is dead. Then it is removed, 
and another atom takes its place, to go through the same 
course of life, action, and death. This succession of parti¬ 
cles, this change from life to death, and this renewal of life, 
are constant, and almost universal, in the animal body. We 
are dying, atom after atom, daily, hourly, momently; and 
we are renewed and revived in the same degree, and at the 
same time. We enjoy, therefore, a constant freshness of 
life. This is the united u r ork of the arteries, which bring 
the new and living atoms, and of the veins and absorbents , 
which carry the old and dead atoms away. The arteries 
and veins have already been described. The absorbent ves¬ 
sels seem to be spread throughout all the textures. Wherever 


NUTRITION. 


113 


there is a minute artery to deposit a living atom, there is an 
absorbent ready to carry it away when it shall have finished 
its life and died. 

245. Dr. Edward Johnson, in his interesting letters on 
“ Life, Health, and Disease,” thus graphically describes 
these vessels: “ There is arising from every point of your 
body a countless number of little vessels, actively engaged in 
the pleasant task of eating you up. They may be compared 
to a swarming host of long, delicate, and slender leeches, 
attached, by their innumerable mouths, to every point of 
your fabric, and having their bodies gradually and progres¬ 
sively united together, until they all terminate in one tail, 
which tail perforates the side of one of the veins at the 
bottom of the neck, on the left side; so that whatever is 
taken in at their mouths is all emptied, by the other ex¬ 
tremity, into that vein, where it becomes mixed with the 
blood.” 


CHAPTER V. 

Action of the Nutrients and Absorbents. — Feeding Sheep on Mad¬ 
der colors Bones. — Balance of Nutrition and Absorption.— In 
Youth, Nutrition, and in Old Age, Absorption prevails. — Both 
more active in the Laborer. — Laborer should eat more Food.— 
Parts that are used more nourished. — Wens and Swellings.— 
Produced by excessive Action of Arteries, and removed by greater 
Action of Absorbents. 

246. The arteries bring the blood, and deposit the new 
particles of flesh, while the veins and absorbents take and 
carry away the old particles. These two systems are con¬ 
stantly at work, antagonizing each other. One set pulls 
down the old fabric, taking it away atom by atom; at the 
same time, the other set rebuilds the fabric anew, and 
replaces the old and the dead with new and living portions. 
In this manner, we are undergoing a perpetual change; 
and we are not precisely the same to-day as we were 
10 * 



114 


PRACTICAL PHYSIOLOGY. 


yesterday. Perhaps we have not now an atom of the flesh 
that we had ten years ago. 

247. Though the individual atoms change, the whole, the 
totality, remains unchanged. The new atoms have the same 
character, the same sympathies, and perform the same func¬ 
tions, as those that went before them. The animal body, in 
this respect, is like a community, or a town of a definite 
number of people. The individual members of this commu¬ 
nity are continually changing; some go out to other towns — 
some die; but their places are filled by others that come 
from abroad, and by some that are born. The individuals 
are not all the same from year to year; and, in course of a 
single generation, they are all exchanged; and yet the body, 
the town, remains unchanged. The same character and 
habits are there, the same principles govern them. The 
community is, in fact, the same, even after every one of its 
original component elements has been removed and replaced 
by others. 

248. The experiment has been tried of feeding pigs and 
sheep upon madder, which is a pink coloring matter. 
When some of these animals were killed, while they were 
living upon this food, the bones were found to be tinged with 
red. But some others were kept, for the same time, upon 
madder, and afterwards were fed, for a period, with hay; 
then they were killed, and their bones were found to be as 
white as those of animals which had never eaten madder. 
There is no doubt that the bones of these last animals had 
been stained with the madder while they lived upon it, and 
that they became white when they again were fed on other 
food. 

249. This is easily explained by the action of their nutri¬ 
ent and absorbent systems. The coloring matter of the 
madder was carried in the chyle to the blood, and in the 
blood to the bone, and there deposited; and, when this is 
absorbed, more red matter is brought and left there; and this 
continues as long as madder is eaten. But, when the food is 
changed, no more red matter is carried to the bones, and 


NUTRITION. 


115 


that which was there is taken away, and its place is sup¬ 
plied with white material. 

250. During the middle periods of life, these two sets of 
vessels are equally active, and usually perform a similar 
amount of work. The arteries carry and deposit as many 
atoms in the flesh as the veins and absorbents carry away. 
The one builds up as fast as the other pulls down; so that, 
though some pounds are added daily to the body, it does not 
gain in weight; neither does it lose, though as much is car¬ 
ried away. But this is not the case at all the periods of life, 
nor in every condition of health. 

251. During the period of youth, and the time of in¬ 
creasing flesh, nutrition predominates; more atoms are then 
brought in Jhe arteries, and deposited, than are taken away 
by the absorbents. When the body is wasting, absorption 
predominates, and carries off more than the arteries deposit. 
When we grow fat, nutrition is the more active; but when 
we grow lean, absorption prevails. The whole of the move¬ 
ments of life are more rapid in the earlier years, and 
slower in old age, than in the middle periods of life. The 
heart beats quicker, the flow of blood is more abundant, and 
both nutrition and absorption are more rapid in the former, 
and slower in the latter period. 

252. Liebig supposes that every action of any of the 
parts of the body is attended with change of particles; that 
when a finger moves, some of the atoms in the muscle that 
produces the motion die and leave their places, and are re¬ 
placed by others. When we move the arm, the legs, or use 
the muscles of any other part of the body, the same changes 
take place in the muscular atoms. All exercise increases 
the activity of both the nutrition and absorption. In order 
to meet the increased demands for new flesh to supply this 
waste during exercise, the heart beats quicker more blood 
is carried to the moving parts; and thus more new flesh is 
formed, as long as more is absorbed. Every one knows that 
the heart beats rapidly, and sometimes almost palpitates, 
while we run or otherwise exercise violently. Those who 


116 


PRACTICAL PHYSIOLOGY. 


suffer from disease of heart cannot make great exertions, be¬ 
cause the heart cannot carry the blood needed to supply the 
greater waste. 

253. The waste of the old atoms of flesh, and the demand 
for new, being increased by exercise, of course more blood 
is then consumed to supply the want which is thus created ; 
and, consequently, more food must be eaten and digested, to 
supply the blood with the new chyle sufficient to repair 
this loss. (§ 127, p. 61.) The laborer must therefore eat 
more than the indolent, and individuals in active youth need 
more food than in quiet old age. But, in inactive life, the 
absorption is comparatively little, and the nutrition and the 
consumption of blood are equally small; there is less de¬ 
mand for food, and a corresponding diminution of appetite. 
If the idle disregards this law of his nature, and eats as much 
as the laborious, the stomach is troubled with the burden ; 
and, if it digests and converts the food into chyle, the blood¬ 
vessels are overfilled with the amount of blood which they 
cannot use, and the whole frame is heavy and sluggish. The 
apostle’s command that, “ if any would not work, neither 
should he eat,” which was given as a moral law, is equally 
binding as a physical law, and cannot be disobeyed without 
suffering. 

254. The processes of destruction and creation have usu¬ 
ally the same comparative activity in all parts of the body, so 
that no part grows fat or lean more than another. But this 
is not always the case. If one organ or part is more active 
than the others, it grows more than they. Thus the arms of 
some laborers, and the legs of others, grow disproportion¬ 
ately large, because they are more used than their other 
limbs. But parts that are not used at all waste away, and 
are often withered. The arm of one of my neighbors was 
palsied about twenty years ago, and it is now shrunken to 
the size of a child’s arm; the unused muscles are nearly 
absorbed. 

255 Wens, and other fleshy tumors, are the effect of the 
unnatural activity of the nutrient vessels, which deposit 


NUTRITION. 


117 


more fatty or other fleshy atoms in the part affected, than the 
absorbents take away. Physicians are often asked to scatter 
these tumors. This is done by stimulating the absorbents to 
a still greater activity than the arteries, so that they may 
carry away more atoms than the others bring. The glands 
of the neck in scrofulous persons sometimes swell, and after¬ 
wards the swelling disappears. A boil often appears upon 
the skin with a prominent and painful swelling; but, without 
coming to a head, or discharging any matter, it goes away. 
In both these cases, the tumor is produced by the superior 
activity of the arteries, and is carried away by the greater 
action of the absorbents. 


CHAPTER VI. 

The Young have fresh and new Atoms of Flesh. —The Aged have 
old Atoms.—Flesh of the Active is new; and of the Idle, old.— 
Blood and Vessels same in all Parts. Vessels select Elements 
from the Blood, in due Proportion, to form the various Textures. — 
Unerring Precision pf Nutrition. — Difference of the Blood in the 
Arteries and in the Veins. 

256. This double work of nutrition and absorption, pro¬ 
ducing changes of the component parts of the body, never 
ceases from the beginning to the end of life. But it is not 
equally rapid in all periods, nor in all persons. In the 
earlier years of childhood and youth, all the processes of 
animal life are more active, and the particles are more fre¬ 
quently changed than in middle life. Consequently, their 
flesh at these periods is ever new and young. But in old 
men, all these operations are more sluggishly and feebly car¬ 
ried on. Their particles are not frequently changed, and 
therefore the atoms of their flesh are old, as well as their 
whole bodies. 

257. As these changes are f-equent in the active and in¬ 
dustrious, their atoms remain but a short time in the living 
body, before they are taken away. This gives them a per- 



118 


PRACTICAL PHYSIOLOGY. 


petual freshness of youth in their flesh; they are, there¬ 
fore, lively and prompt in action. These changes take place 
more slowly in the inactive; their atoms remain a longer 
time; and their flesh is therefore always old, and indisposed 
to action. It is easy to see this difference between the en¬ 
ergy and sprightliness of one who has always accustomed 
himself to action abroad, and the heavy sluggishness of 
another, who has lived delicately, and avoided exercise. 
Compared with his years, the one is ever young, while the 
other is ever old. 

258. We have no means of knowing how, or by what 
means, the final work of nutrition is done. We only know 
the instruments with which it is accomplished, and the ma¬ 
terials that are used. Anatomists have examined the blood¬ 
vessels, and chemists have analyzed the blood, and have 
taught us the shape of one and the composition of the other; 
and there our knowledge stops. We cannot penetrate any 
farther into the mysteries of nature. So far as the eye of 
man can discover, the blood-vessels are the same in structure 
and character, in all the organs and textures of the body, 
and the same blood is found in all. And yet, with a wonder¬ 
ful precision, these little nutrient vessels select out of this 
common storehouse of nutriment just those elements, and in 
just their varied proportions, that are needed to form the 
various kinds of flesh and substance that compose the ani¬ 
mal body. 

259. In the fat, the organs of nutrition select from the 
blood 79 parts of carbon, 11£ parts of hydrogen, and 9£ 
parts of oxygen; and with these form fatty atoms. In the 
hair, they take 50 parts of carbon, 6 parts of hydrogen, 17 
parts of nitrogen, and 26 parts of oxygen and sulphur, and 
make an atom of hair. And from the blood in the muscle, 
they take 51 parts of carbon, 7 parts of hydrogen, 15 parts 
of nitrogen, 21 parts of oxygen, and 4 parts of other mat¬ 
ters, and form muscular pai tides. In a similar manner, the 
vessels of the brain select the brain ; and in the skin, and 
in all other organs, they select the very kinds and proportions 


NUTRITION. 


119 


of the elements that compose each, and no other. They 
take just enough of each element, neither more nor less, and 
combine them in the due proportion of each kind, to form 
the part which is wanted. 

260. Although the different textures of the animal body 
are so nearly alike in their composition, and so slight a vari¬ 
ation would produce another kind of flesh, yet, in health, no 
mistake is made. Each organ and texture receives flesh of 
its own kind. Muscle is not deposited in the brain, nor bone 
in the muscle, nor tendon in the liver. In every part, the 
blood-vessels act with such unvarying and beautiful precision, 
and perform their work with such faithfulness to their pur¬ 
pose, that they might almost seem to be endowed with a 
special intelligence, if we were not assured that they, even 
the minutest of them, are under the constant supervision and 
direction of that paternal Providence, without whose notice 
not an atom moves nor a sparrow falls to the ground. 

261. Thus all the atoms of flesh, all the parts of the ani¬ 
mal body, were first in the stomach, and next in the arteries; 
and then they became living flesh, and acted a while, and died. 
Then, again, all these, with the exception of the hair, the 
nails, and the outer skin, which grow out and fall, are once 
more taken into the vessels, and are found in the veins. 
The blood in the arteries differs from that in the veins, in its 
nature and its composition. In one, it is scarlet, rich, nutri¬ 
tious, loaded with new particles of digested food, and is 
therefore capable of giving life and strength to any of the 
textures. In the other, it is dark purple ; it has lost its rich 
particles, and is therefore innutritious; it is also loaded with 
the dead and wasted particles that have lived and died in the 
body. If the venous blood be thrown into the arteries, and 
circulated through the system, it not only must fail to nourish 
and give new particles of flesh to the textures, but, with its 
wasted and offensive burden, it must carry disease or death 
to the body. 

262. The veins are incessantly receiving additions of the 
particles of the exhausted flesh, and would soon be so over- 


120 


PRACTICAL PHYSIOLOGY. 


loaded as to be incapable of action, if there were not some 
means provided to carry these out of the body. This might 
seem a difficult matter. These dead atoms are in the veins, 
and those are buried in the deepest recesses of the body, 
apparently beyond the reach of any external influence, and 
without any outlet to the world abroad. But Nature has no 
difficulties. Her means are always adequate to her wants. 
Her process of relieving the living body of those useless and 
burdensome matters is made simple and easy, by means of 
the lungs and respiration, and of the skin and perspiration. 


PART III. 
RESPIRATION. 

CHAPTER I. 

Wasted Particles carried out of the Body. — Composition of Blood in 
right Side of the Heart. — Lungs protected by Bones of Chest. — 
Spine. — Breast-Bone. — Ribs. — Position of Ribs. 

263. The wasted particles of the animal body — those that 
have lived and have been a part of the living system — have 
been removed from their places in the various organs, and 
carried into the veins, and through them to the right side 
of the heart. As nutrition and absorption are continually 
going on in the body, these old particles must accumulate in 
the veins and heart; and, as they amount to several ounces a 
day, they would soon overload and destroy the living system, 
if they were not carried out from it. This is done; and 
they find an outlet through the lungs as fast as they are 
removed from their original places of life and action in the 
various textures. 

264. The venous blood — that which is gathered in the 




RESPIRATION. 


121 


right side of the heart, from all the various parts of the body — 
consists of three kinds of materials : 1st, the residue of the 
arterial blood after nourishing the body, or that which is left 
after the particles have been selected for the nourishment of 
the textures; 2d, the old and dead atoms of flesh; and, 
3d, the chyle, or digested food brought through the Iacteals. 
Neither of these three elements can nourish the body. The 
remnant of the arterial blood has lost much, if not all, of its 
life-giving qualities. The dead particles would be poisonous 
if carried round again; and the new chyle is not yet pre¬ 
pared to furnish nutriment. They must, therefore, all be sub¬ 
mitted to some process by which the first shall be strength¬ 
ened, the second carried out of the body, and the third 
perfected, before this blood can be used again to nourish the 
body. All this is done by means of the air in the lungs. 

265. The lungs of man are placed within the chest, 
at the upper part of the trunk. They are organs of ex¬ 
ceeding delicacy in their p IO , XV. Bones of the Chest, 
structure, and would not 
bear with impunity any 
exposure to external in¬ 
jury. They are therefore 
protected with great care. 

They are covered on all 
sides with a bony frame¬ 
work, which prevents all 
contact with external ob¬ 
jects. The bones which 
compose the walls of this 
chest are so arranged, and 
fixed with joints and mus¬ 
cles, that they admit of 
very free motion, and al¬ 
low to the internal cavity 
great range of expansion 

and contraction, for ad- a p rea st bone. h,b. Back-bop©) 
mitting and expelling air. c c c,c. Ribs. 

U 



122 


PRACTICAL PHYSIOLOGY. 


266. The chest (Fig.XV.) extends from the neck to the ab¬ 
domen. It is conical in shape, being small at its upper end, 
and larger at the lower part. It is enclosed by bone at the top 
and on its sides, and by muscle at the bottom. The breast¬ 
bone, a, (Fig. XV. p. 121,) is in front; the spine, b, b, or 
back-bone, is behind; and the ribs, c, c, c, cover the sides of 
the chest. 

267. The spine, or back-bone, is composed of twenty-four 
bones, called vertebrae, which are connected by thick layers 
of very strong and elastic cartilage, or gristle, between them. 
These give to the column great flexibility and freedom of 
motion, and such strength that, through all the chances of 
accidents and violence, these bones are very rarely broken or 
displaced. Yet it may be bent in any direction, and is capable 
of sustaining great burdens that may be placed upon the head. 
Twelve of these bones form part of the chest, and to these 
twelve vertebrte or bones of the back are attached twenty-four 
ribs, twelve on each side. 

2G8. The breast-bone , a , is thin and flat, reaching from the 
neck to the region of the stomach. It is covered with so little 
flesh as to be perceptible to the touch. At the lower end is 
attached a cartilage or gristly substance, that extends about 
two or two and a half inches downward, and ends in a point 
at the pit of the stomach. This breast-bone forms the front 
pillar of the chest, though by no means an immovable one, for 
it rises and falls with all the motions of the ribs. 

269. The ribs y e, c, c, compose the principal part of the 
framework of the chest. They surround the cavity from the 
back to the breast-bone, covering all the sides and most of 
the anterior and posterior portions of the cavity. All are 
joined to the back-bone by their posterior end, and ten o ‘ 
them are connected with the breast-bone by their anterioi 
ends. Some of these are fixed directly to the breast-bone; 
others terminate in cartilages of an inch or more in length, 
that extend to the breast-bone; by which arrangement these 
ribs have a great freedom of motion. 

270= The ribs nearly surround the chest, somewhat as 


RESPIRATION. 


123 


hoops surround a barrel. But their course is not horizontal, 
They incline downward from the back-bone to the breast¬ 
bone in front; consequently, the diameter of the chest is so 
much lessened by this obliquity of position; but when the 
ribs are raised to a horizontal position, at right angles with 
the axis of the chest, this diameter is increased, and the 
capacity of this cavity is enlarged. This is 
easily shown by the experiment of putting 
a large hoop obliquely upon a barrel of 
smaller diameter. The hoop, «, c, in its ob¬ 
lique position, touches the barrel; but, if the 
hoop be raised horizontally to 6, it would ex¬ 
tend beyond the cask, and allow' it a much 
greater expansion. 


Fig. XVI. 



CHAPTER II. 

Movements of Ribs-Diaphragm. — Expansion of Chest in Inspira. 

tion_Contraction in Expiration. — Size of expanded and con- 

tracted Chest. 

271. The posterior ends of the ribs are attached to the 
back-bone, and fixed. The motions are all made with the 
anterior ends, which are free. They are joined to the spine 
in such a manner that they can only move upward and down¬ 
ward, not from side to side. The spine being the pillar 
upon which the frame of the chest rests, it is fixed and im¬ 
movable in breathing; but all the movements of the ribs and 
breast-bone are made upon it. These are lifted up and fall 
down at every respiration. 

272. The first or upper rib is fixed and motionless; the 
second has very little motion; the third has more motion 
than the second; and the fourth more than the third. This 
motion goes on increasing to the eleventh and twelfth, which 
move very freely. There are several muscles which are at- 




124 


PRACTICAL PHYSIOLOGY, 


tached to the back-bone and to the ribs, and fill all the 
spaces between them. Some of these are attached by one 
end to the spine, and, running obliquely forward and down¬ 
ward, are attached by the other end to the ribs below. 
Others are attached by one end to one rib above, and by 
the other end to another rib below. When these muscles 
contract, they lift the ribs. The posterior end of each rib 
rolls in its socket in the spine; but the main portion of the 
bone is raised and carried outward, and the whole cavity of 
the chest is then expanded, in the same manner as the hoop 
(Fig. XVI.«,c.) would allow the cavity of the cask to be ex¬ 
panded, if the side c were lifted to the level of the side a , 
which is supposed to be fixed. 

273. The ribs, spine, breast-bone, and muscles (Fig. XV. 
p. 121) bound the chest on all its sides. As this cavity is 
conical, there is hardly any surface at the top. But there is 
a broad and extensive surface at the bottom of the cone, 
which is covered by a flat muscle, called the diaphragm. 
(Fig. II. e?, p. 19.) This performs a part of the greatest 
importance in the work of respiration. It is the flexible 
partition that divides the chest from the abdomen, and sep¬ 
arates the respiratory from the digestive organs. Its edges 
are attached to the back-bone, and to the lower edge of the 
lower ribs, to the breast-bone, and to all the lower part of 
the chest. It forms an arch, upon the upper or convex 
surface of which the lungs rest; and in the hollow below 
some of the organs of the abdomen — the liver, stomach, 
&c. — are placed. 

274. When the diaphragm is at rest, its arch points upward 
into the chest, as the bottom of a common glass bottle is 
turned into its cavity; and its upper point reaches as high as 
the fourth rib, and, consequently, must very materially lessen 
the capacity of the chest, and press upon the lungs. But 
when it is in action and contracted, the arch is drawn down, 
and, leaving a space behind, enlarges the capacity of the 
chest, and allows more room for the lungs to expand. The 
diaphragm is the dividing-wall between the lungs and diges- 


RESPIRATION. 


125 


tive apparatus. (Fig. V. c?, p. 19.) The lungs lie in contact 
with it above, (Fig. V. a, 6, p. 19,) and the digestive appa¬ 
ratus lies in contact with it below. (Fig. Y. e, f, p. 19.) 
When it is expanded, it rises into the chest, and the lungs are 
pressed up, and the abdominal organs follow immediately 
behind. And, on the other hand, when it contracts and 
lessens the arch to give expansion to the lungs, it must 
press the abdomen and its contents downward and out¬ 
ward. A simple and easy illustration of the operation 
of the diaphragm in breathing, may be found in the com¬ 
mon India-rubber bottle. If we hold this in one hand 
and press the bottom inward with the finger, the air is 
forced out through the neck. If, then, we remove the fin¬ 
ger, the bottom returns to its natural position, and then the 
air flows through the neck to fill the increased cavity. 

275. By these two combined actions of the muscles of the 
ribs and of the diaphragm, the chest is enlarged. The mus¬ 
cles on the sides of the chest raise the ribs, and extend their 
circle forward and outward. The diaphragm draws down 
its arch from the fourth to below the seventh rib, and thus 
enlarges the chest; and the lungs having room for expan¬ 
sion, the air is pressed into them to fill the vacuum left by 
the enlarging chest. This is the mechanical part of the pro¬ 
cess of inspiration. 

276. After the chest is thus sufficiently expanded, the 
muscles of the ribs and the diaphragm relax and lose their 
firmness. Then the action of other muscles, aided by the 
elasticity of the cartilages, carries the ribs downward ; and, in 
going down, they lessen the diameter, and consequently the 
capacity of the chest, by bringing the sides nearer to each 
other, and the breast-bone nearer to the back-bone. At the 
same time, the muscles that cover the abdomen press upon 
its contents, and force them against the diaphragm. This 
yields to the pressure, and rises upward and presses upon the 
ungs, which retreat before it, and the air is expelled. This 
is the process of expiration. 

277. Fig. XVII. represents an outline of the front view of 

II* 


PRACTICAL PHYSIOLOGY. 


126 

the expanded and contracted chest. The full lines d , d, d. 
show the size of the cavity when the ribs are drawn down 
and the diaphragm is expanded upward. The dotted lines 

Fig. XVII. Outline of the Expanded and Contracted Chest. 
Front View. 



show its size when the ribs are lifted and the diaphragm 
drawn down. When the ribs are at rest, they lie downward 
and inward, and their surface is represented by the lines 
d , d , d , d , d, d; but, when they are raised, they are carried out¬ 
ward, and their surface is represented by the dotted lines 
h , h , b, b , b, b. When the diaphragm is at rest, it projects 
upward in form of the line e, e, e; but, when it is in ac¬ 
tion, it is drawn downward in form of the line c, c, c. 
The upper point e reaches as high as the fourth rib. The 
upper point c reaches as high as the seventh rib. It is now 
very plain that the cavity 6, b, b, c, c, c , b, b, b , is larger than 
the cavity d , d, d , e , e , e, d, d, d, and the difference in size 
must be in proportion to the extent of the motions of the ribs 
and the diaphragm. 


RESPIRATION. 


127 


CHAPTER III. 

Lungs. — Situation. — Textures. — Windpipe — Glottis. — Organ ot 
Voice. — Air-Tubes and Cells. — Mucous Membrane. — Coughing. 

— Interweaving of Air-Vessels and Blood-Vessels. — Inspiration 

— Expiration. — Respiration. — Cooperation of Parts. 

278. The lungs are situated within the chest, which has 
been now described. There are two lungs, (Fig. XVIII. 
«, 6,) placed one on the right, and the other on the left side 
of the chest. The heart lies between them, (Fig. XVIII. g ,) 
and these completely fill this cavity. (Fig. V. a , 6, c .) The 
lungs are very soft and spongy. They contain little or no 
flesh, but are composed almost exclusively of tubes and cells, 
which are to be filled, some with blood, and others with air. 


a , Left lung. 

ft, Right lung. 

c, Windpipe. 

d, Heart. 

e, Great artery 
carrying blood to 
lungs. 

/, Great vein. 

ff, Great artery- 
carrying blood to 
the body. 

1 


Fig. XVIII. Lungs and Heart. 



279. The air-tubes begin at the back part of the mouth 
and nostrils with a single cylinder, which leads through the 
neck to the chest; but in the lungs they are divided and sub- 
divided into smaller and smaller tubes, which are distrib- 







128 


PRACTICAL PHYSIOLOGY. 


uted throughout the whole respiratory organs. The blood¬ 
vessels (§ 225, p. 103) proceed from the heart in large trunks, 
and, like the air-tubes, are divided and multiplied until they 
terminate in minute branches of imperceptible size, which 
lie in contact with, and spread over, the air-cells. Then 
these little blood-vessels are again gathered together into 
larger and larger tubes, until, at last, they form two large 
trunks, that enter the heart. These trunks are of the same 
size as those which left the heart to carry the blood to the 
lungs. 

280. The windpipe, or trachea , is composed of somewhat 
stiff rings of cartilage or gristle, so that it is easily felt in 
the front of the throat. The upper end of this tube is usu¬ 
ally open; but the epiglottis (§§ 20, 21, 22, p. 16) is 
placed there to cover over and protect this passage when¬ 
ever the food passes over it, on its way from the tongue to 
the oesophagus. But, when we are not swallowing, this 
valve stands open. 

281. The upper end of the windpipe opens into the back 
chamber of the mouth, by a narrow chink, called the glottis. 
This is made by the approximation of the two sides of the 
tube, so that the air may produce sounds when it passes be¬ 
tween them. Some muscles, which are attached to these 
sides,, draw them more closely together, or allow them to 
separate. By thus opening or narrowing this chink, the 
sounds which are made by the air passing through it, are va¬ 
ried. This is the organ of voice; and these sounds are the 
various tones which we utter in language, in singing, or in 
crying. When this part of the windpipe is diseased by 
what is called a cold in the throat or otherwise, these tones 
are changed, and often destroyed. A man then loses the 
control of his voice, and can neither sing nor talk as he does 
in health. Sometimes the voice is entirely destroyed or sus¬ 
pended, and then the sufferer can only speak with the mouth 
in a whisper. A gentleman, whom I have seen while writing 
this chapter, has not been able to speak a loud word for three 
months, in consequence of ulceration about the glottis. 


RESPIRATION. 


129 


282. At the junction of the neck with the chest, and just 
Dehind the top of the breast-bone, the great air-tube, the 
windpipe , is divided into two tubes, or bronchi. One of 
these goes to the right, the other to the left lung. After 
entering their respective lungs, they divide into smaller 
branches or tubes, as represented in Fig. XIX. These 

Fig. XIX. Windpipe and Air-Vessels of the Lungs. 


a. Windpipe. 

b. Left lung. 

c. Great branch of the air-tube 
going to the right lung. 

d. d, d. Minute branches of the 
air-tubes. 

e. e. Air-cells at the minute 
termination of the air-tubes, mag¬ 
nified. 

tubes do not divide so minutely as the blood-vessels, but ter¬ 
minate somewhat abruptly in a great number of minute cells. 
(Fig. XIX. e , e.) These cells are estimated to be one hun¬ 
dredth of an inch in diameter. They are so numerous as to 
be distributed to every part of the lungs; and the extent of 
the inner surface of the whole, collectively, is estimated vari¬ 
ously by physiologists. Some suppose it to be 20,000 square 
inches; others thirty times the whole surface of the body. 
But all agree that there is a very extensive surface presented 
to the action of the air. 

283. These air-tubes and air-cells are lined with a mucous 
membrane of exceeding delicacy, which, during the whole of 




130 


PRACTICAL PHYSIOLOGY. 


life, will bear the presence of pure air, but will not tolerate, 
for a single moment, the presence of any other substance, 
not even a drop of water, as most of us have had occasion to 
know in some part of our lives. This lining is thin and 
sensitive, and very liable to be disordered. Most of our 
colds and catarrhs are but affections of this membrane. 
And our coughs are mostly caused by some irritation applied 
to it, or derangement in it. Whenever it is not in a com¬ 
fortable condition, — when it is dry for want of mucus, or 
covered with too much of it, — or when any particle of food, 
or any other foreign substance, is lodged in any part of the 
air passages or cells, or even gets within the glottis, — then 
nature sets up a violent expulsory effort to press the air out 
suddenly, and to blow and force away the intruder, or relieve 
the irritation. This is coughing. 

284. We perceive this sometimes when we breathe dust, 
or offensive gases, or pungent matters, all of which irritate 
and offend this sensitive texture. But, delicate as it is, it 
may, by use, lose its sensibility, and become accustomed to 
bear very injurious substances, as the sole of the barefoot 
boy loses its delicacy, and will bear the rough surface of the 
street without suffering; and as the hands of the smith and 
of the dyer lose much of their sensitiveness to heat, so that 
they can, without apparent pain, handle iron and plunge into 
dyes so hot as to burn others; so the membrane of the lungs 
becomes used even to tobacco-smoke, and bears its frequent 
and almost perpetual presence, without appearing to suffer 
any harm. 

285. The heart is placed about the middle of the chest, 
and between the lobes of the lungs, (§ 205,) (Fig. XVIII. 
p. 127,) and sends its blood-vessels to the right and to 
the left, through each of these lobes. These vessels ramify 
through every part of the organ, and are interwoven with the 
air-tubes. (Fig. XX.) These myriads of minute arteries come 
in contact with the air-cells, and are separated from them 
only by an exceedingly thin membrane, so thin that gases 


RESPIRATION. 


vn 

can pass through it from the air-cells to the blood-vessels, 
and from the blood-vessels to the air-cells; but it is suffi¬ 
ciently thick to prevent the passage of fluids. 


FIG. XX. Interweaving of the Air-tubes and Blood-vessels in 

the Lungs. 



a. Windpipe. 

A, c. Right and left lung. 

d. Heart. 

e , e. Divisions of the great air- 
tubes going to the right and left 
lungs. 

f f. Pulmonary arteries carry¬ 


ing the blood from the heart to the 
lungs. 

g, g. Pulmonary veins, carrying 
the blood from the lungs to the 
heart. 

h. h, h, h. Air-cells at the termi¬ 
nations of the air-tubes. 


286. When the ribs are lifted and the chest expanded at 
the sides, and the diameter thereby increased, and when the 
diaphragm is drawn down, and the chest enlarged below, 
there must be a vacuum within this cavity to be supplied by 
air. The only passage into the chest is through the mouth 
and windpipe, and into the lungs; consequently, when the 
cavity of the chest is enlarged, the air rushes into the air- 




132 


PRACTICAL PHYSIOLOGY. 


tubes, and fills all the air-cells. On the other hand, when 
the ribs fall, and the abdominal muscles press upon the 
digestive organs, and force the diaphragm to rise, the lungs 
are compressed, the air is expelled, and the air-cells closed. 

287. During life, there is a constant succession of these 
actions. The air is at one moment drawn into the lungs, by 
the contraction of the diaphragm and the lifting of the ribs, 
and at the next moment it is expelled, by the falling of the 
ribs and the contraction of the abdominal muscles. These 
two operations constitute what is called respiration. Each 
respiration supplies the lungs with a new quantity of air. 

288. This is the operation of respiration. All the parts 
of its apparatus, — the framework of bone, the muscles of the 
ribs, and the diaphragm, — all cooperate in the work, and are 
necessary to effect its purpose, which is to bring the air 
and the blood together, and to relieve the latter of its impu¬ 
rities, and fit it for the support of the living body. 


CHAPTER IV. 

Waste Particles. — Carbon. — Air, Composition of. — Oxygen. — 
Nitrogen. — Affinity of Oxygen for Carbon. — Carbonic Acid.— 
Carbon meets Oxygen in the Nutrient Vessels. — Blood absorbs 
Oxygen from the Air, and gives out Carbonic Acid. 

289. The respiratory apparatus and its operation, which 
carry out from the body the dead and waste particles, afford 
striking evidences of Nature’s skill, and beautiful illustra¬ 
tions of her handiwork. The principal elements of this 
waste matter, now mixed with the venous blood, are carbon 
and hydrogen. These have a stronger affinity or attraction 
for oxygen, one of the elements of the air, than they have 
for the fluid of the blood in which they move. 

290. Carbon is one of the most important elements of the 
animal body. It enters into and forms a part of all flesh, 
and of all vegetable matter. The brain, the muscle, the 



RESPIRATION. 


133 


fat, and the bile, the solid fibre of the wood, the pulp of 
the cherry, and the flour of the grains, are all composed, in 
a great proportion, of this substance. Hydrogen , also, is 
a very essential element in the composition of flesh. Com¬ 
bined with oxygen, it forms water; and in this state it is 
* und in the fluids, and in the more solid textures of the ani- 
ial body. But it is also found, in different combinations, 
vith carbon, oxygen, and nitrogen, in the various kinds of 
flesh. 

291. It will now be necessary to examine the composition 
of the air. This is apparently a simple element; nothing 
seems purer or less compounded than air, as we breathe it. 
But chemical analysis shows it to be composed of two ele¬ 
ments, — oxygen and nitrogen, — in about the proportions of 
twenty-one parts of oxygen to seventy-nine parts of nitrogen. 
Beside these, there are generally some other gases, — a little 
carbonic acid gas, and a little vapor, — amounting to one or 
two per cent., in the atmospheric air. 

292. Oxygen is one of the most prevalent substances in 
nature. It enters into the composition of all animal and 
vegetable matter, and is the perpetually necessary element 
of life, in all its forms, and in all its stages. It is the essen¬ 
tial ingredient of most acids. With sulphur it forms sulphu¬ 
ric acid; with nitrogen, in large proportion, it forms nitric 
acid, or aqua fortis ; and, in smaller proportion, atmospheric 
air; with hydrogen, it forms water; and with carbon, car¬ 
bonic acid. In air it is a gas; in water it is a liquid. 
When separated and alone it is a gas; in the rust of iron it 
is solid. 

293. Nitrogen forms about four fifths of the volume of the 
air we breathe. It is a little lighter than air, and, of course, 
lighter than oxygen. It unites with oxygen in several propor¬ 
tions, forming very different substances, according to the pro¬ 
portions of their mixture. Nothing is more mild and bland 
than air, and few things are more caustic and harsh than 
aqua fortis, which is a combination of the same elements. 

294. Although nitrogen and oxygen are apparently so 

12 




134 


PRACTICAL PHYSIOLOGY. 


closely united, yet the oxygen has a stronger affinity for car¬ 
bon and hydrogen than for nitrogen; and whenever, under 
appropriate circumstances, the carbon or hydrogen is pre¬ 
sented to the air, the oxygen leaves the nitrogen and unites 
with the carbon, and forms carbonic acid, or with the hydro¬ 
gen, and forms water. In other words, the air is decom¬ 
posed, its simple elements are separated from each other, and 
a new compound is formed by the union of carbon and 
oxygen, or by the union of hydrogen and oxygen. 

295. Carbonic acid is a composition of oxygen and car¬ 
bon. This is a gas heavier than air, and lighter than water. 
If it be in a vessel with water, it rises to the top; and if in 
a vessel with air, it sinks to the bottom. It is so much heavier 
than air that it can be poured from one tumbler to another, 
like water. It is found in some caves, and at the bottom of 
some wells. It is the fixed air which is the product of fer¬ 
menting bread, beer, wine, and cider, and fills the bubbles 
that rise to the top of these liquids at the time of their fer¬ 
mentation. When the beer is drawn out from the vats, in 
the great breweries, this gas often falls to the bottom, and 
partially fills these reservoirs. It is also the product of com¬ 
bustion of charcoal; and often, where this fuel is burning 
without any outlet near the floor for this gas to run off, or a 
chimney of sufficient draft to carry it upward, it partially or 
entirely fills the room. Wherever this gas is, there can be 
no pure air, for this is excluded by it as certainly as it would 
be by water; and it is as unsafe for a man to enter a cavern, 
well, vat, or a room containing it, and carry his head below the 
surface of this gas, as it would be if these contained water. 

296. When the chest expands, the air rushes in and fills 
all the air-tubes and the air-cells throughout the lungs. 
There it comes almost in contact with the venous blood, 
which is distributed in the numberless little vessels, and 
separated from the air-cells only by a thin film of membrane, 
through which the gases can pass. There an interchange 
takes place between the fluid and the gas. The blood ab¬ 
sorbs from the air some of its oxygen, and the air takes from 


respiration. 


135 


the blood some of its carbonic acid and its water. By this 
change the blood is relieved of its exhausted and dead parti¬ 
cles, and receives new and life-giving particles in their stead. 
The color is changed from a dark purple to a bright scarlet. 
After this, the blood is ready again for the sustenance of life, 
and is sent back, through the pulmonary veins, to the left 
side of the heart, to be sent again, through the arteries, to 
the whole of the body, carrying nutriment to support it, and 
oxygen to combine with its dead carbon. 

297. Carbon and hydrogen compose the principal portion 
of the wasted and exhausted particles of the living body , and 
these are thrown into the veins. There they meet with the 
oxygen that has been absorbed from the atmosphere in the 
lungs, and carried in the blood, through the arteries, to the 
capillaries and the minute veins. There these, the hydrogen 
and the carbonic particles, and the oxygen, meeting together, 
unite and form carbonic acid gas and water. These new 
compounds are then sent, with the venous blood, through 
the veins, to the heart, and thence to the lungs. 


CHAPTER V. 

Venous or purple Blood changed to arterial or scarlet Blood. — 
Color of venous Blood seen in Veins of Hand, and of arterial 
Blood in flushed Cheek. — Oxygen consumed in Respiration. — 
Carbonic Acid given out. — Water given out through Lungs.— 
Other Matters. — Foul Odors in Breath. — Offensive Breath. 

298. The blood enters the lungs a compound of three 
kinds of matter — the old blood, which had not been used for 
the purpose of nutrition, the old wasted particles, which 
are now seeking an outlet, and the new chyle from the 
digestive organs. (§ 264, p. 120.) All this heterogeneous 
mass is unfit for the nutrition of the animal body. Its color 
is purple. In this compound no free oxygen is present, but 
carbonic acid and water are abundant. When the blood. 



136 PRACTICAL PHYSIOLOGY. 

returns back to the heart from the lungs, it is one homoge¬ 
neous compound; it has lost its carbonic acid and water, and 
received a supply of oxygen, which now pervades the fluid. 

299. The difference of the color of the blood is seen in 
the veins of the hand and arm, which appear to be blue, 
while the flushed cheek is of scarlet red, from the presence 
of the blood in the arteries of the skin. When a person is 
bled from the arm, the vein is opened; the blood that flows 
is venous, and of course purple. The inexperienced mistake 
this natural color for the effect of disease, and often remark, 
“ that the blood is very black; the patient needed bleeding 
to be relieved of such dark impurities.” 

390. This change of the blood is effected in the lungs ; 
of course, there must be a corresponding change in the air. 
The oxygen which the blood receives is the oxygen of the 
air; and the carbonic acid and water which are thrown off* 
from the blood are mingled with the air. The air is therefore 
changed by this process, and to this extent. Experiments 
very carefully tried show that air, when once respired, con¬ 
tains about eight per cent, more carbonic acid than before, 
and that the oxygen is diminished in proportion necessary 
to form this acid. If the same air be respired over and 
over several times, all the oxygen is consumed, and the 
air becomes loaded with carbonic acid gas. 

301. Sir Humphry Davy enclosed one hundred and sixty 
cubic inches of air in an oiled silk bag, and breathed this 
for the space of one minute. In this time, he made nineteen 
respirations. On examination of the air, he found that 
nearly one half (^f ;f-) of the oxygen was consumed, and its 
place supplied by 15.2 inches of carbonic acid, which had 
been generated in the blood-vessels, and given out from the 
lungs in one minute * 

302. The quantity of carbonic acid gas which is found 
in the air that has been breathed, varies in different circum¬ 
stances, and in different conditions of the human body. 
The experiments all concur in showing that it is a great deal, 


Muller’s Physiology, p. 295. 


RESPIRATION. 


137 


and that the same air, if repeatedly respired, soon becomes 
saturated, or so completely filled with it that it can receive 
no more. Allen’s and Pepy’s experiments show that one 
hundred inches of air, once respired, contained eight and 
one half inches of carbonic acid gas, and that no continu¬ 
ance of the respiration of the same air could make it take 
up more than ten per cent, of this gas. 

303. Besides the carbon of the blood, which is to be car¬ 
ried away through the lungs, there is water which is not 
needed in the body, and which finds its passage through the 
same outlet. This water goes out in the form of vapor, and 
ordinarily is not perceptible. But every one is familiar with 
the visible cloud of vapor that accompanies his breath in a 
cold winter’s morning. This is but the condensation of the 
vapor that is invisible in a warm day. The same may be 
ascertained at any time by breathing on a looking-glass, 
when the vapor is condensed, and becomes visible in the form 
of water. 

304. There are other matters carried olf from the body 
through the lungs by the air. Their perceptible qualities 
differ in various men. The breath from one is sweet, from 
another sour, from a third foul and offensive, and from a 
fourth, it is without perceptible odor. These disagreeable 
odors may, in some cases, proceed from decayed teeth, or 
from disease in the mouth, the air passages, or the lungs; 
but more commonly they come from direct secretions in the 
lungs of certain matters, which existed previously in the ani¬ 
mal body; as, when one has eaten onions, his breath smells 
of garlic. The odor of wine or spirits which have been 
taken into the stomach, is perceptible in the breath, long 
after the mouth has been thoroughly cleansed of these mat¬ 
ters. In other cases, these unpleasant odors proceed directly 
from some foul secretion in the lungs. The habit of chew¬ 
ing or smoking tobacco gives to one’s breath an odor pecu 
liarly offensive to others who may inhale the same air. In 
some persons, this odor is so powerful as to taint the air of a 
whole room as soon as they enter it. 

12 * 



138 


PRACTICAL PHYSIOLOGY. 


CHAPTER VI. 

Air changed by Respiration unfit to be breathed again. — Dyer col¬ 
ors with Dye of full Strength. —Air should have full Proportion of 
Oxygen. — Respired Air, loaded with Carbonic Acid Gas, can take 
away no more. — Air saturated with Water can take no more 
from Lungs. — Air spoiled for Respiration in three Ways. 

305. An examination of the air, after it has passed out of . 
the lungs, shows that it is very different from the same air 
before it went in. At first, it had about twenty-one per cent, 
of oxygen, seventy-eight per cent, of nitrogen, and one per 
cent, of carbonic acid; but, when it has been respired, it has 
lost about one fourth of its oxygen, and has gained carbonic 
acid and .vapor, in proportions varying with many circum¬ 
stances connected with the state and health of the animal 
system. If, then, it is necessary for the blood to consume at 
each respiration one fourth of the oxygen of the air which 

is inhaled, it would follow that, if the same air be breathed 
twice, one half of the oxygen would be consumed; and if 
breathed three times, three quarters; and if breathed four 
times, all would be consumed. If so much oxygen is not 
consumed, there must be so much less of the carbon and 
the waste of the blood carried away. 

306. But, if the lungs consume only one fourth of its oxy¬ 
gen at each respiration, it by no means follows that the air 
can be breathed four times over, and at each time have the 
same effect in purifying the blood. In respect to relieving 
the blood of the carbon, the oxygen may be considered as 
the strength of the air. When this constitutes twenty-one 
per cent., it is of full strength; when it is only fifteen per 
cent., it is only three quarters of full strength; and, at most, 
it can have only three quarters of the due power. So, when, 
after being once respired, it is reduced by another and 
another respiration to one half and one quarter its full 
strength, it, of course, has so much less power of performing 
that which is required of it. 


RESPIRATION. 


139 


307. When the dyer has determined what strength of dye 
will give the due color to his cloths, he adds fresh coloring 
matter as often as one piece has weakened it, in order to 
keep up the dye to its full strength, and to give to each suc¬ 
cessive piece of cloth the same hue; for, if the dye be 
weakened, it will give a weaker color. He would not, there¬ 
fore, continue to dip his cloths in it, after it is reduced, be¬ 
cause there was some coloring matter left; nor would he 
think of exhausting all the power of the dye, unless he was 
satisfied to produce a duller shade. 

308. Precisely analogous to this is the effect of the air 
in purifying the blood of its corrupting carbon. The stronger 
the air, — that is, the greater the proportion of its oxygen, — 
the more effectually will this carbon be carried away; the 
weakened air must produce a weak effect, and take away less 
of the impurities. Air, therefore, which has been breathed 
once or more, having lost a certain part of its oxygen, must 
be, in that proportion, unfit to do the work of respiration. 
If we breathe pure oxygen, or air too strongly oxygenated, — 
that is, air containing more than twenty-two per cent, of this 
gas, — the carbon would be taken from the blood faster than 
it could be spared, and the body would be wasted. If we 
breathe air containing less than twenty-one or twenty-two per 
cent, of oxygen, it will not carry the carbon off so fast as is 
required. It is only by breathing air of the natural strength 
that this work is best performed, and the carbon carried 
away neither too rapidly nor too slowly. Air, therefore, 
should be breathed once, and once only. We need a fresh 
draft of air at every inspiration, as much as the dyer needs a 
fresh dye at every coloring. 

309. Air, when it has been breathed, not only loses its 
oxygen, which is its active principle, but it is loaded more 
or less with carbonic acid gas, which is increased by every 
respiration. Therefore, when we breathe air over and over, 
we not only breathe a weaker gas, but a fouler one; we 
receive back into the lungs, and into the vital system, that 


140 


PRACTICAL PHYSIOLOGY. 


dead and corrupting matter which nature had so carefully 
removed. 

310. There is another consideration in this matter. Sup¬ 
posing the air were merely a passive vehicle to carry off the 
carbonic acid gas, and had no active duty in the work, it 
would be a natural question to ask, How much of this gas 
can it bear away? Is there any limit to its capacity of 
taking up and bearing off this offending matter? Now, it is 
well established that the air will not receive and hold an in¬ 
definite quantity; but, after having received a certain propor¬ 
tion, it will receive no more. When it has arrived at this 
point of saturation, — that is, when it is so full that it can 
receive no more, — it then is useless as a vehicle to carry off 
any more from the lungs. Bernan says* that, when the air 
holds in solution only about three and a half per cent, of its 
bulk of carbonic acid gas, it is unfit for respiration. 

311. The air, for this purpose, may be considered as the 
water which the dyer would use to wash his colored cloths. 
It is plain that, when the water is once befouled or saturated 
with the loose coloring matter, it would take no more from 
the cloths; and therefore the judicious cleanser changes his 
waters as often as they become foul; and, whenever he can, 
he selects a running stream, so that the water is carried 
away as fast as it is befouled, and its place is supplied with 
fresh and clean. 

312. Upon the same principle, the lungs cannot be thor¬ 
oughly cleansed of the impurities which come to them 
through the blood, unless the air is supplied to them fresh 
and untainted at every respiration. For foul air, loaded with 
carbonic acid gas, can no more cleanse the lungs, than foul 
water can cleanse the colored cloths. 

313. The blood is relieved of its superabundant water 
through the lungs. If this does not find an outlet here, and 
if it is not carried off by the air, it must be carried back in 
the blood to the heart and the arteries, to overload the sys- 


Art of Warming and Ventilation. 


RESPIRATION. 


141 


tem and impede its operations. There is a definite quantity 
which must be carried out, and the air has a limited capacity 
for holding water, and of taking it away. When this limit is 
reached, and the air is saturated with water, it can take up 
no more. The air would be saturated with moisture from 
the lungs in about the same number of respirations that 
would consume its oxygen; after this, it would be useless for 
the removal of either carbon or water. 

314. Thus we see that, in three ways, the air becomes 
vitiated, and unfit for continued respiration : 1st, by the con¬ 
sumption of its oxygen, so that it is unable to remove the 
carbon from the blood; 2d, by being loaded with carbonic 
acid gas, so that it cannot take it up any longer from the 
lungs; 3d, by being saturated with moisture, so that it can¬ 
not aid in relieving the system of its superabundance of 
water. 


CHAPTER VII. 

More Oxygen consumed, and Carbonic Acid given out, in cold and 
dense Air, and less in warm. — Air on Mountains does not sup¬ 
port Life as in Valleys. — Impurities in Air diminish Oxygen.— 
Feeble, consumptive, and melancholy Persons give out less 
Carbon and Hydrogen. 

315. The amount of oxygen received, and the quantity 
of carbonic acid gas and watery vapor carried off, differ at 
different times, and vary with varying circumstances. A 
dense atmosphere is more concentrated, and, consequently, 
contains more oxygen in a given space, than a rare one. The 
air is more expanded in a warm than in a cool climate, and 
in hot than in cold weather. We therefore do not inhale so 
great a weight of air, and, consequently, so great an amount 
of oxygen, in summer as in winter. The oxygen received 
being less, the carbonic acid given out is diminished in the 
same proportion. 



142 


PRACTICAL PHYSIOLOGY. 


316. We experience faintness and languor in the warm 
season, because the air does not purify a sufficiency of blood 
for the vigorous sustenance of the system. Then people 
complain that “ the air is heavy,” which is directly opposite 
to the truth, for the air is really light, and it does not contain 
sufficient oxygen to invigorate them, and give sufficient 
strength and elasticity to bear the burdens and operations of 
life easily, and hence all these are heavy to them. We ob¬ 
serve animals puff and breathe rapidly after running in sum¬ 
mer, and we do the same on any active exertion, more in 
warm than in cold weather. We do this to bring a more 
frequent supply of air to the blood, and thus to compensate 
for the lightness of the air, and deficiency of oxygen, by the 
rapid renewal of both. 

317. The air is more dense in the lower regions of the 
earth, and on the level of the sea, than on the heights of 
mountains. As we ascend from below to the higher eleva¬ 
tions, we find the air lighter and more expanded, and we are 
compelled to breathe more rapidly. Travellers all complain 
of the increasing languor and faintness as they ascend, and 
enjoy the bracing and invigorating effect of the air as they 
come down the mountains. 

318. All kinds of impurities in the air, and every thing 
that diminishes the proportion of oxygen, have the same 
effect of weakening or diminishing the vital properties of the 
air. In some mines, a gas is given out, called the^re damp , 
which is carburetted hydrogen. Whenever this is present, 
it lessens the vivifying power of the air, by excluding its oxy¬ 
gen. If it is breathed in small quantities, it occasions gid¬ 
diness, sickness, and diminished nervous power; and, when 
it is in great proportion, the miners are unable to breathe, 
and often fall a sacrifice to it. 

319. The general state of the system affects the quantity 
of matter which is carried out through the lungs. When 
the whole frame is well, and all the functions are carried on 
vigorously, — when the circulation of the blood is easy and 
the respiration well sustained, — then the old particles of the 


RESPIRATION. 


143 


body are freely separated, and the new and vitalized ones 
take their places, and the former are carried rapidly away, 
and life is frequently renewed, and vigorously sustained. 
But when the system is feeble and languid, — when it is fever¬ 
ish and generally disturbed, — when it is exhausted by fa¬ 
tigue or want of sleep, — the reverse happens ; the circulation 
is languid, the nutrition feeble, absorption slow, and a smaller 
proportion of carbon and hydrogen is carried off. 

320. The system is relieved of these dead matters, more or 
less, according to the condition of the lungs, in proportion 
as they are healthy or unhealthy. In some diseases, their 
texture is changed from an exceedingly porous and spongy 
body, to one partially or entirely solid. In consumption, 
a part of these organs is filled with tubercles, or abscesses. 
Sometimes these occupy almost the whole substance of the 
lungs, and leave so little room for air that respiration can¬ 
not be carried on. Then the sufferer literally dies for want 
of breath, because the lungs cannot receive sufficient air to 
purify as much blood as is necessary to sustain life. The 
impure blood which comes to the lungs, to exchange its car¬ 
bon for oxygen, does not find air to give it relief, and goes 
back to the heart nearly as corrupt as when it came out. 

321. In lung fever, and some other diseases, a portion of 
the lungs becomes solid, like liver, and the air-cells are 
closed. If the whole of the lungs becomes consolidated, 
death must follow; but this state more frequently prevails in 
a part only of these organs ; then the blood is sent back in an 
imperfect condition, and the frame is then only partially nour¬ 
ished. Some have sustained life for a considerable period 
with only one sound lung; but theirs was a feeble and lower 

| life, and they could not perform all the work, nor enjoy all 
the comforts, of ordinary well-sustained existence. 

322. The states of the mind and feeling, as well as those 
of the body, affect the discharge of waste matters through 
the lungs. Cheerfulness and exhilaration, and the exciting 
passions, increase the separation of carbon ; while the de¬ 
pressing emotions — fear, grief, and anxiety — diminish it. 


144 


PRACTICAL PHYSIOLOGY. 


CHAPTER VIII. 

Lungs must have Capacity to receive sufficient Air. — Action of 
Respiration performed by the Muscles of Chest and Diaphragm.— 
Ribs spread outward in Inspiration. — Action of Diaphragm 
presses the Abdomen downward and outward. 

323. It is not only necessary that the lungs should be in 
good health, and be supplied with pure air, but they should 
be able to receive it in sufficient quantity. This implies that 1 
the chest should be of the natural size, and that it should 
have the due power and opportunity of expansion and con¬ 
traction. 

324. Although it is absolutely necessary that the air 
reach the blood in the lungs, yet it has no active power to 
get there. It is merely passive. It does not enter of its own 
accord, but it is pressed into these organs, when, by the en¬ 
largement of the cavity, a vacuum, or rather, more room, is 
made for it. Nor have the lungs any active power of expan¬ 
sion. They, too, are merely passive. Their air-cells do not 
extend themselves, and thus press the walls of the chest 
outward. But, when these walls are extended, the air rushes, 
or rather it is pressed, into these air tubes and cells, and com¬ 
pels the lungs, thus filled with air, to swell and completely fill 
the cavity of the chest. 

325. The structure of the chest is arranged like the com¬ 
mon bellows for expansion and contraction. (§§ 270—277, pp. 
122,125.) The bony framework is furnished with joints, on 
which the ribs move. The muscular covering contracts and 
sets this framework in motion, while the diaphragm draws 
down, and both cooperate to enlarge the internal capacity 
of the pulmonary cavity; then the ribs fall, and the abdom¬ 
inal muscles press the diaphragm up, and both combine to 
diminish this cavity. 

326. In Fig. XXI., the full black lines represent the out¬ 
line of the chest and the abdomen when the lungs are empty, 
and the dotted lines represent the same when the lungs are 


respiration. 


145 


filled with air. When the air is inhaled, the walls of the 
chest are expanded from a , e , to 6, and the diaphragm 
drawn down from e, d , to b , rf, and consequently the walls of 
the abdomen are carried from e, c, to b, c, and the diameters 
of both are increased. 

Fig. XXI. •S'icfe Fiew o/* expanded and contracted Chest. 


e, d, Diaphragm drawn up. 
b , d, Diaphragm drawn down. 

a, e, c, Front wall of contracted 
abdomen. 

a, by Cy Front wall of expanded ehe 
domen. 


327. This expansion of the chest and abdomen cannot 
take place unless there is room outwardly. If the body is 
enclosed in any inelastic girdle or dress which fits it closely 
when the chest is empty, it must be confined within that 
limit, and its expansion prevented. 

328. Some of the fashions of the dress of females of 
modern times, and in civilized nations, have precisely the 
effect of bandages to confine the ribs, and limit the expansion 
of the chest, and prevent the inhaling of the due quantity of 
air. The corsets are made of inelastic materials, and usu. 
ally so constructed and laced as to exactly fit the shape of 
the bust, and lie as closely to the surface as possible. When 
these are worn, and the other garments are arranged upon 








146 


PRACTICAL PHYSIOLOGY. 


the same principle, and with their fastenings bound closely 
to the body, so as to mould the form, they confine the ribs, 
and prevent their movements upward and outward. 

329. In this confinement of garments, whenever the mus¬ 
cles attempt to raise the ribs and extend them outward, they 
meet with resistance. These muscles are not very strong; 
they are made for a definite purpose — merely to raise the free 
ribs, and to expand the unobstructed chest, but not to break 
bands, force lacings, or stretch layers of compact cloth. 
Hence, finding all labor ineffectual, they after a while cease 
their attempts to move the ribs, or at least diminish their 
exertions very materially, and leave the main business of 
respiration to be done by the diaphragm. 

330. When the diaphragm descends out of the chest, it 
must press the digestive organs downward before it. But 
these organs cannot be compressed; they are not made to 
occupy less room than before; they are merely removed from 
their upper position to a lower and a broader one. There¬ 
fore they must find room for extension below and outward. 
And if this is prevented, — if the abdomen is so bound or 
compressed that it cannot expand, — the stomach and liver 
cannot give way before the diaphragm, and then this muscle 
cannot descend to make room for the lungs, nor can we 
breathe by this part of the respiratory apparatus. 

231. The consequence is, whenever the fashion of the 
female dress extends the pressure of the waist beyond the 
ribs, and encloses a good portion of the abdomen, unless quite 
loose, or whenever the costume of the male presses upon 
this part of the body, it must interfere with the freedom of 
motion of that part of the system, and so far prevent or 
restrict respiration by the diaphragm 


RESPIRATION. 


147 


CHAPTER IX. 

Common Notion of Beauty of Chest unnatural. — Chest Seat of most 
important Organs. — Size of Chest corresponds to Size of Body. — 
Natural Chest not conical. — Shape of Bones changed by Pres 
sure. — Comparative Form of Chests! 

332. There is a common and mistaken notion of beauty 
of the female chest. The beau ideal of many requires that 
it should be of a small and taper form, diminishing from 
the shoulders downwards to the waist. This opinion is 
encouraged and strengthened by the fashion of female gar¬ 
ments. But however general this form may be, and however 
long established in the world, it is artificial, and not natural. 
It is opposed to that principle of beauty which nature has 
clearly and every where established — that grace is secondary, 
and not primary; that it is the proper and becoming arrange¬ 
ment of those parts that are necessary and useful. 

333. The chest is not a mere connecting link between 
the upper and lower portions of the animal frame; but it is the 
depository and the workshop of some of the most important 
of the vital organs, without the action of which life cannot 
be for a moment sustained, and without whose free and 
perfect operation life must be impaired and enfeebled. 

334. As the chest is made for the use of the body, and 
not for ornament, — as it was created to contain the heart, 
and to give room and motion to the lungs, so that respiration 
could be carried on in the best manner, — it would follow that 
that form and size of this part of the animal frame is the 
most beautiful, which would best answer these purposes, and 
allow the lungs to perform their functions most effectually. 

335. The size of the chest should bear a proportion to 
the size of the body, so that it may receive a quantity of air 
proportioned to the quantity of blood that must be purified 
in the system. Therefore, a small waist becomes only a small 
person, and a large waist is necessary to the grace of a large 


148 


PRACTICAL PHYSIOLOGY. 


person, precisely as a large or small head is becoming to a 
frame proportionally large or small. 

336. This is the plainly established principle of Nature. 
We see it in all her works. If we examine the little child, 
who has never worn any close dress, we find the circumfer¬ 
ence of its chest about as great as that of the body at the 
hips, and a line from the arm-pit to the hip would be nearly 
straight. If the waist is never subjected to the pressure of 
clothing, which would interfere with the motions of the ribs, 
the chest will be continued through life in nearly the same 
shape as that of the child, (Fig. XXIII.,) or of the Indian 
female, whose garments have never been bound about the 
chest. We see the same in many laborers, more especially 
those from the middle and the north of the continent of Eu¬ 
rope. The ancient statues show the full chest, the expanded 
waist, and the broad freedom of the lungs for motion. 


Fig. XXII. 


Fig. XXIII. 




337. But the chests of many who are incased in a close 
costume are small and taper downwards from the shoulder 












RESPIRATION. 


149 


to the waist, (Fig. XXII.) In some, this is the temporary 
effect of present pressure; and when the close garments are 
taken off, the ribs rise to their natural position, and the chest 
expands to its natural size. But in others, whose chests 
have been long subjected to this close confinement, this dis¬ 
tortion of ribs and contraction of chest become fixed and 
permanent ; and then they need no outward covering to con¬ 
fine the respiratory organs within these narrow dimensions. 

338. Figure XXIII. represents the chest of those who have 
always worn loose dresses. Fig. XXII. is that of one used 
to tight dresses. The former receive much more air into 
their lungs, and carry off the impurities of their blood more 
freely, and hence their changes of particles must be more 
rapid, their vigor and elasticity of body must be much 
greater than the others enjoy. 

Fig. XXIV. Fig. XXV. 

Bones of a natural Chest. Bones of a distorted Chest. 



339. The bony frame by pressure may be altered , and 
made to assume forms very different from that which nature 
intended. In the process of nutrition, (§§244-247, pp. 112, 
114,) the old particles of the animal body, in all its parts, 
are continually going away, and new ones are taking their 
places. But if any pressure bear upon the depositing vessels 






150 


PRACTICAL PH YSIOLGY. 


on one side and close them, the new particles are not placed 
there, but the blood is poured more freely into the other side, 
and there the growth is increased; and thus the shape of the 
organ, the bone, or the flesh, is changed. 

340. This distortion necessarily follows in the form and 
size of the ribs, from the pressure of corsets or any tight 
clothing upon them. They gradually yield to the external 
form, and, bending inward, assume the shape which the outer 
mould makes for them; and the chest, which was originally 
of a size in due proportion to the rest of the body, now be¬ 
comes permanently small, and the internal capacity of the 
lungs corresponds to the external measurement. Fig. XXV. 


CHAPTER X. 

Action of Diaphragm is affected by State of Stomach. — Frequency 
of Respiration, Capacity of Lungs, Amount of Air inhaled, should 
correspond with the Carbon and Water that are to be carried away. 
— Quantity of Blood in the Body.— Quantity of Blood and Air 
flowing through Lungs. 

341. The free operations of the diaphragm are sometimes 
impeded by the disorders of the stomach. In some forms of 
dyspepsia, the sufferer feels as if the cavity of the chest were 
already filled, and that no more air could be inhaled. He 
breathes short, and is often convinced that there must be 
serious disease of the lungs. In some of these cases, the 
stomach is distended with gas, and presses upward upon 
the diaphragm so as to prevent its motions downward. In 
other cases, the peculiar kind, rather than the quantity, of 
gas affects this organ and impairs its power of motion. 

342. A man in good health will breathe about eighteen 
times a minute. Some breathe more rapidly than this ; oth¬ 
ers not so frequently. Children and women breathe more 
rapidly than men. Exercise, especially fast running, quick¬ 
ens the respiratory movements. So, also, the exhilarating 
affections — cheerfulness — laughter — have the same effect. 



RESPIRATION. 


151 


On the other hand, fatigue, depression of spirit, grief, and 
anxiety, diminish the frequency of respiration. 

343. The lungs of a man of average size, and in usual 
health, when at rest, when neither expanded nor contracted, 
will hold two hundred and ninety cubic inches, or a little 
less than a gallon of air. But, when distended by ordinary 
inspiration, they receive forty inches more. This will make 
three hundred and thirty inches, when full. This forty 
inches is the usual extent of respiration. This is the amount 
of air which the lungs need, and which they receive at every 
inspiration, when allowed freedom of motion, eighteen times 
a minute, and one thousand and eighty times an hour. 

344. This quantity of pure air is not merely wanted to fill 
the capacity of the chest and lungs, but it is needed for the 
purification of the blood. Bearing in mind that the blood 
receives from the system carbon and hydrogen of which it 
must be relieved; and knowing that it receives with the 
chyle more water than is wanted; and that, when these are 
combined, they go to the lungs to be disburdened of their 
superfluous and noxious elements; it is natural to sup¬ 
pose that the amount of air should correspond with the 
quantity of these matters, which are thus to be removed. 

345. Then in order that the air may meet the wants of 
the blood, the size of the chest corresponds to that of the 
body, and the motions of the ribs and the expansion of the 
lungs correspond to the flow of the blood. This one would 
suppose to be the case from a mere general view of the har¬ 
monies of nature; for the Creator makes all his works con¬ 
sistent one with another. 

346. The quantity of blood in the whole system of a man 
of average size, amounts to about twenty-eight pounds. 
(§ 232, p. 107.) The heart beats in a man about seventy-five 
times a minute, and forces out of itself about two ounces, or 
half a gill, at each pulsation or contraction ; and, consequent¬ 
ly, in one minute, more than nine pints of blood are sent 
to the lungs to be acted upon by the air. In the same time, 
twenty-three pints of fresh air are brought into the lungs; and 


152 


PRACTICAL PHYSIOLOGY. 


the amount of carbon in the nine pints of blood corresponds 
very nearly with the capacity of the twenty-three pints of air 
to carry it away. 


CHAPTER XI. 

Air spoiled by Loss of Oxygen and by Carbonic Acid Gas. — Capaci¬ 
ty of Air to receive Vapor. — More Air saturated by Vapor of 
Breath in cold than in warm Day. — Vapor from Skin saturates 
some Air. — Amount of insensible Perspiration. — Quantity of Air 
spoiled by Loss of Oxygen, by Carbonic Acid, and by Water. 

347. Breathing air once destroys or weakens, and, par¬ 
tially at least, spoils, for the purpose of respiration, 720 cubic 
inches of air a minute, by the mere consumption or use of its 
oxygen. On this account, we need about one half a cubic 
foot of air every minute. When the air goes out from the 
lungs, it contains about eight or nine per cent, of carbonic 
acid gas, (§ 302, p. 136;) but if it contains more than three 
and a half per cent, of this gas, it is unfit to be breathed 
again. 

348. It necessarily follows, then, that the air which has 
been once breathed, contains about two and a half times this 
proportion, and therefore the quantity of this injurious gas 
that is the product of one respiration, is sufficient to corrupt 
nearly once and a half as much more. The quantity which 
is exhaled in one minute would give three and a half per 
cent, to 1800 inches, and render so much unfit to be breathed 
again. 

349. There is a limit to the power of the air to take up 
and carry away the watery vapor from the lungs, and this 
limit differs with the temperature. When the air is cooled 
down to 32°, or freezing point, a cubic foot of it will hold 
about two and a half grains of water in solution. When it 
is raised up to 65°, which is usually the proper temperature 
of sitting-rooms, it will hold a little more than seven grains ; 
and at 90°, which is \ery nearly the temperature of the air 



RESPIRATION. 


153 


when it goes out from the lungs, it will hold fifteen grains. 
This vapor is invisible, and generally imperceptible. But if 
the air at 90°, containing fifteen grains in a cubic foot, be 
cooled down to 32°, it then can hold only two and a half 
grains; and the difference between these quantities — twelve 
and a half grains — will be condensed and become visible in 
the form of water. 

359. The cloud of vapor which one seems to expire in a 
cold day, is caused by this condensation. If, in winter, one 
or more persons sit in a room sufficiently warm to be com¬ 
fortable, the air becomes filled with pulmonary vapor. If 
the temperature of the room is the same throughout, this 
vapor is imperceptible to the eye; but the air near the win¬ 
dows, if these are not double, becomes cooled by the action 
of the outward air, and then this vapor is condensed, and 
lodged upon the glass in the form of water. If the air 
abroad is cooled below freezing point, this condensed vapor 
freezes upon the windows, and the glass becomes coated 
with a layer of ice. So we usually find the windows of our 
sleeping-chambers covered with ice from this cause, in the 
cold mornings of winter. 

351. The whole of the water thrown off from the lungs in 
this state of vapor amounts to upwards of twenty ounces in a 
day,* which will make six grains and two thirds a minute. 
This will saturate nearly one half a foot of air at 90°; but, 
as air usually contains about one grain of vapor in each 
cubic foot, it can absorb so much less, and more air will be 
saturated with the pulmonary vapor. 

352. The insensible perspiration is another and very 
fruitful source of moisture in the air. The skin is a very 
active agent, and is incessantly throwing off watery vapor 
from its surface. When this runs freely in drops, it is called 
sweat , and seems to be very abundant. But this is only a 
small part of the whole of this fluid, which is thrown off 
through the external surface; for a much greater quantity 
is sent off in an invisible form. 

# Library of Useful Knowledge. 




154 


PRACTICAL PHYSIOLOGY. 


353. The quantity of this insensible perspiration varies 
from twenty ounces a day in the northern, to forty ounces a 
day in the southern, countries of Europe. Carpenter esti¬ 
mates it to be thirty-three ounces in England; this is eleven 
grains a minute; others give a much higher estimate. Cruik- 
shank’s experiments demonstrated it to vary from twelve to 
forty-five grains a minute; and he assumes the mean, from 
persons of both sexes, of average size, and in good health, 
to be twenty-three grains a minute. Taking the last as the 
standard, and adding these twenty-three grains to the six 
grains and two thirds of vapor thrown out from the lungs, 
we have enough to saturate somewhat more than two feet 
of air with moisture; and, so much air being saturated, it 
can take no more vapor from the lungs. 

354. Thus we see that, in these three ways, the air loses 
its power of relieving the blood of its superfluous carbon and 
water, and is thereby rendered unfit for the work of respira¬ 
tion;— first, by the loss of its oxygen, in each minute, 
720 inches; secondly, by saturation with carbonic acid gas, 
1800 inches; thirdly, by saturation with vapor from the 
lungs and skin, 3590 inches. 


CHAPTER XII. 

Seven to ten Feet of Air spoiled each Minute. — Want of fresh Air 
in Houses, but not provided. — Size of Parlors, and Number of 
Occupants. — Small Sleeping-Chambers. — Lodging-Rooms in 
Boarding-Houses, and in temporary Houses. — Cabins of Steam 
and Canal Boats. 

355. About four cubic feet of air being rendered by each 
person partially or entirely useless for the purpose of purifying 
the blood and giving it new life , it will, of course, be neces¬ 
sary that we have so much new and fresh air supplied every 
minute for each one. If this, after having been once breathed, 
or saturated with vapor, were carried immediately away, this 



RESPIRATION. 


155 


quantity would be sufficient; but, as the corrupted air min¬ 
gles with the pure, this is partially corrupted; therefore we 
need a larger supply to support respiration. The best au¬ 
thorities on the subject of ventilation consider seven feet as 
the least that should be supplied to each person; and Dr. 
Reid allows ten feet. Taking the lowest estimate, seven feet 
will be considered as necessary for the maintenance of the 
healthy respiration of each person. 

356. If we always dwelt in the fields, we should have 
fresh air enough, without any effort on our part. But when 
we live in closed houses, it becomes a question whether we 
are thus supplied, and the wants of nature are satisfied; and, 
if our rooms are made air-tight, then it is necessary to deter¬ 
mine whether they contain air sufficient for the consumption 
of all that inhabit them, as long as they stay there. If this 
be not the case, then it is necessary to find some means to 
carry off the foul air as fast as it is rendered so by respira¬ 
tion, and to bring in a new supply from abroad to take its 
place. 

357. A continued supply of fresh air for all inhabited 
rooms is as necessary as a continued supply of heat in cold 
weather. And yet provision is not usually and intentionally 
made to meet this necessity in the arrangements of our dwell¬ 
ings and our public rooms. The architect and the builder 
provide carefully for warmth, but they generally make little 
or no provision for respiration. Fortunately, the imperfec¬ 
tion of the builder’s work obviates, in some small degree, 
and generally prevents, the immediately destructive conse¬ 
quence of the defects of the architect’s plans. It is difficult 
— almost impossible — to make a room so tight that no air 
can force itself into it, when the internal atmosphere is 
heated, or vitiated by respiration. 

358. A room sixteen feet square, and nine feet high, will 
contain 2304 cubic feet. This will be sufficient for four 
persons less than an hour and a half for ordinary day pur¬ 
poses. This room, though not so large as some that are 
inhabited by day or by night, is yet as large as most, and 


156 


PRACTICAL PHySIOLOGY. 


much larger than many rooms so occupied. It is esteemed a 
proper economy to have small and tight parlors and sitting- 
rooms, for the occupation of the families during the day and 
evening. The average of these do not probably contain 
more than 1709 feet. If only four persons inhabit one 
of these, they would have air sufficient for less than one hour. 

359. It is considered, by many, a prudent architectural 
design, to have many and small sleeping-chambers. Room 
for the bed and wardrobe, and for convenient dressing, is all 
that is thought absolutely necessary. At least, the plan of a 
good dwelling generally includes a portion of these narrow 
chambers. Many of these will not contain more than 500 
cubic feet; and in such, two grown persons, often more 
than two children, sleep during the night. Here is air 
enough to last two persons a little more than half an hour. 

360. In public boarding-houses, in some taverns, and in 
the houses where the operatives of factories are boarded, it 
is an object to lodge the family as cheaply as possible. Con¬ 
sequently, the lodging-rooms are often made as small, or to 
hold as many sleepers, as they can. Oftentimes these lodgers 
are so closely crowded, as to have hardly air enough for half 
an hour’s respiration. At one of our large manufacturing 
establishments, eight sleep in one chamber containing 2574 
feet; in several other chambers, two have 262£ feet, four 
have 1800 feet, six have 973£ feet, four have 686^ feet, for 
a night’s respiration. These rooms contain air enough to 
supply their occupants from twenty-five to sixty-six minutes. 

361. This close crowding of sleeping-chambers is carried 
to the greatest extent in some of the lodging-houses built for 
temporary use on some of the railroads, and other public 
works. I have the measure of one of these chambers. The 
room was in the attic, — sixteen feet long, and fourteen feet 
wide. The height was six feet ten inches in the middle, but 
the roof met the floor at the sides, so that the average height 
of the room was three feet five inches, and the whole cubic 
contents of this chamber were 765 feet. There were no 
means whatever provided for the ventilation of this room 


RESPIRATION. 


157 


There was neither window nor door. The only opening 
made into the chamber was a small hole in the floor, through 
which the sleepers ascended from the room below. This 
lower room was not ventilated much better. It had less 
than 1400 cubic feet of space; and there nineteen persons 
boarded or lived in the day, and five slept at night, and there 
all the operations of cooking, eating, and washing were 
carried on. 

362. In this chamber, with less than 800 feet of air, four¬ 
teen men slept through the night; and for eight hours these 
men breathed over and over the air from each other’s lungs, 
in the vain attempt to purify their blood, and refresh their 
frames, and invigorate themselves for the next day’s labor. 
Here was air provided sufficient to last them less than nine 
minutes, and yet it was required to last them 480 minutes; 
and in this, as well as in other crowded chambers, nothing 
but the undesigned ventilation through the crevices of the 
imperfect carpentry, saved these sleeping occupants from 
suffocation. 

363. The crowded state of the cabins of steamboats, in 
which the sleeping apartments are below decks, and of the 
canal boats at night, leaves less air for respiration than even 
these rooms. Not unfrequently, fifty or even sixty persons 
sleep in the narrow cabin of a canal boat, which contains 
no more space than some of the airy chambers where only 
two cautious people would usually spend the night. 


CHAPTER XIII. 

Crowded Workshops. — Chambers. — Public Halls. — Churches. — 
School-Rooms. — School-Rooms filled with foul Air. — Habit of 
breathing each other’s Expirations. — Foul Air offensive. — Ven- 
tilation. 

364. Some of the trades require a very small space for 
their operations. The shops in which these are carried on 
14 



158 


PRACTICAL PHYSIOLOGY. 


are therefore constructed in reference rather to the conve¬ 
nience of the work, and the economy of heating them, than 
to the health of the workmen. Consequently, these men are 
sometimes so crowded and confined as to have insufficient 
air for respiration. In a room ten feet square, and eight 
feet high, with 800 feet of air, six and sometimes eight men 
can work, without interfering with each other; and this is 
thought good accommodation. 

365. Family rooms, lodging-chambers, cabins, and shops 
are not the only places where men and women gather in 
numbers beyond the capacity of the air to support their 
healthy respiration. Public rooms, lecture-rooms, churches, 
concert halls, and, above all, school-rooms generally, are 
badly ventilated. They are not supplied with air sufficient 
for the ordinary numbers, and still less for the occasional 
crowds, that meet in them. The general plan of these is to 
hold many persons; and the idea of the architect is to so 
arrange the seats, that the greatest possible number may be 
gathered into a given space. 

366. A part of these pages on respiration were read as a 
lecture before an associated audience, which assembled in a 
hall forty-seven feet long, thirty-seven feet wide, and nine 
feet high, measuring 15,650 cubic feet. This room is made 
to hold five hundred persons when full; and usually from 
three to four hundred meet there. In the former case, there 
are thirty-one feet, and in the latter thirty-nine to fifty-two 
feet of air for a person. The sittings of this society vary 
from one to three hours. 

367. A church which has been recently built has one 
hundred and eighty-three feet of air for a person, in an av¬ 
erage audience, and one hundred and thirty-six feet when 
crowded. Another has from seventy-five to ninety-nine feet 
of air for each of the people, according to their numbers. 
Many other churches afford about the same proportion of 
air to their occupants. I have not their exact measurement, 
as of these above stated; but the foulness of the air which 
one perceives on entering them late in the forenoon, or in the 


RESPIRATION. 


159 


afternoon, too plainly shows that they have not sufficient 
ventilation. 

368. In times of great excitement, the crowds in the 
churches or halls are more dense even than these. It is esti¬ 
mated by those observant of the matter, that, in the closest 
crowds, a man standing will not occupy more than two 
square feet of surface; and therefore a room can hold half 
as many as there are square feet of floor. This would give 
twice as many cubic feet of air as the height of the room 
above the heads of the people. I have stood in Faneuil 
Hall when each man had very little more space for air than 
that which was over his head to the ceiling above. 

369. School-houses seem to be as imperfectly supplied 
with air as public halls. It is rare that one enters a school¬ 
room from the fresh air abroad, after the scholars have been 
in a few minutes, without perceiving the foulness of the 
atmosphere within. A room thirty feet square is ordinarily 
supposed to be large enough for eighty or ninety children; 
and, if the room be nine feet high, this will allow eighty or 
ninety feet of air for every child, which is sufficient for their 
respiration twelve or thirteen minutes. The air of these 
rooms becomes loaded with carbonic acid gas, with the foul 
secretions of the lungs, and the excretions of the skin. It 
is offensive, so much so as sometimes to produce sickness 
and faintness in those who enter from the external air. 

370. But “not the least remarkable example of the power 
of habit is its reconciling us to practices which, but for its 
influence, would be considered noxious and disgusting. We 
instinctively shun approach to the dirty, the squalid, and the 
diseased, and use no garment that may have been worn by 
another. We open sewers for matters that offend the sight 
or the smell, and contaminate the air. We carefully remove 
impurities from what we eat and drink, filter turbid water, 
and fastidiously avoid drinking from a cup that may have 
been pressed to the lips of a friend. On the other hand, we 
resort to places of assembly, and draw into our mouths air 
loaded with effluvia from the lungs, skin, and clothing of 


J60 


PRACTICAL PHYSIOLOGY. 


every individual in the promiscuous crowd — exhalations 
offensive, to a certain extent, from the most healthy individ¬ 
uals ; but when arising from a living mass of skin and lungs, 
in all stages of evaporation, disease, and putridity, prevented 
by the walls and ceiling from escaping, they are, when thus 
concentrated, in the highest degree deleterious and loath¬ 
some.” * 

371. When one enters any rooms thus crowded, and 
inhales the air thus exhausted and corrupted, he perceives, 
at once, an offensive and oppressive smell, and there comes 
a feeling of suffocation about his throat and chest, followed 
by some degree of faintness. But those who live in it, hav¬ 
ing by degrees become accustomed to it, do not perceive the 
smell; the sensibility of their lungs and nostrils is blunted; 
they are not offended with the foul odor of the atmosphere; 
yet their lungs do not find the oxygen to purify the blood, 
and cannot perform their work successfully. They are not 
relieved of the waste of dead atoms of flesh within them. 

372. It is evident that unless there is some way of re¬ 
moving the respired and foul air from these rooms, and of 
replacing it with new and fresh air from abroad, the work of 
respiration cannot be carried on as it should be, the blood 
cannot be purified of its dead particles, and the system can¬ 
not be nourished with life and energy; and then the con¬ 
ditions which nature established for our existence cannot 
be fulfilled. 

373. Ventilation, or the means of supplying fresh air to 
every inhabited room, every parlor, sleeping chamber, school - 
house, public hall, church, or shop, in which people live, is, 
then , as necessary as the supply of food. After the air already 
in the room is consumed or vitiated, it must be removed, and 
as much brought in every minute as is used or spoiled. There 
must, then, be two constant currents; one outward, carrying 
off the foul air, and the other inward, bringing in pure air. 
The outward current may pass upward through the chimney, 


* Beman, Art and History of Warming and Ventilation, Vol. II. p. 313. 


RESPIRATION'. 


161 


or through the crevices in the upper part of the ceiling, or 
through a passage-way provided for the purpose. The in¬ 
ward current more commonly comes through the uninten¬ 
tional crevices which the skill of the architect and mechanic 
seldom entirely prevents, and which admit air sufficient to 
save the occupants from the death of the Black Hole, but 
not enough to save them from some sickness, or faintness, 
or certainly some depression of life. As those crevices are 
inadequate to supply the air that is needed to sustain the ful¬ 
ness of life, every room that is inhabited, and especially every 
hall that is filled with people, and every school-room, should 
be provided with means of ventilation sufficient to admit and 
to carry away at least seven feet of air a minute for each oc¬ 
cupant. For this purpose, a school-room, with forty persons, 
should have a ventilator a foot square, through which the air 
should move upward at the rate of two hundred ond eighty 
feet a minute, and as much fresh air should be received.* In 
ordinary circumstances, air cannot be compressed ; no more 
can be received into a room than is carried out. It is there¬ 
fore useless to provide means for the admission of fresh air 
by a furnace or otherwise, unless there be some avenue, 
either accidental or designed, for the foul air to escape. 
Nor can a room be emptied of air; none will go out unless 
as much comes in. A ventilator will not, then, carry away 
the foul air, unless there be some place accidentally left, or 
especially provided, for the admission of other air to take 
its place.f 


* This current of air upward is accelerated by placing a large burning lamp 
in the flue of the ventilator. In most school-houses, a larger ventilator — 
one measuring four or more square feet — will be better, and will carry off 
the foul air sufficiently with a slower current. 

f “ Experiments have been made, in a room prepared expressly for the pur¬ 
pose; and in the House of Commons, everyday of the session, for two years; 
and the results show that it was rare to meet with a person who was not 
sensible of the deterioration of the air when supplied with less than ten cubic 
feet per minute.”— Wyman on Ventilation. 

For the best practicable methods of ventilation of dwelling-houses, school¬ 
rooms, and public halls, Dr. Wyman’s valuable work can be advantageously 
consulted. 


14* 



162 


PRACTICAL PHYSIOLOGY. 


CHAPTER XIV. 

Connection between Fulness of Life and Respiration. — Hybernating 
Animals stupid. — Man is lively or dull in Ratio of Respiration. — 
Consumptive Persons have less Energy of Life. — Diminution of 
Air and Respiration lowers Life. — Lodgers in unventilated Cham¬ 
bers unrefreshed in Morning. 

374. Nature has connected a fulness, buoyancy, and 
energy of life with the amount of respiration. Reptiles, 
snakes, frogs, have a small respiratory apparatus; they 
breathe but little, and are dull, heavy, and inactive. They 
have comparatively little muscular energy, and little nervous 
power. As we ascend in the scale of animals, we find the 
correspondence between the activity of their respiratory 
functions and their general vital energy to be more and 
more manifest. Birds have more life and muscular power 
than other animals, and they have a fuller development of 
their respiratory apparatus, and breathe a freer air. Man, 
also, has a larger preparation for breathing, and more ener¬ 
gy of nervous and of muscular life. 

375. The hybernating animals retire to holes and cav¬ 
erns in winter; and there they spend the cold season in a 
torpid, insensible, almost lifeless state. But, in the spring, 
they come out with new life and activity. In the dormant 
state, the hedgehog breathes only four or five times, and 
the dormouse eight or nine times, a minute, and both with 
so little motion as to be scarcely perceptible. While their 
respiration is thus feeble, all their voluntary functions, their 
power of motion, and their sensations, seem entirely sus¬ 
pended, and their vital energies reduced to the lowest point 
consistent with the bare continuance of life. 

376. But the warm weather of spring gives them a new 
life; then the lungs again expand, and work with their ac¬ 
customed activity; the blood circulates freely; the old par¬ 
ticles are taken away, and new ones supply their places, and 
respiration carries off the offensive matters, and the whole 


RESPIRATION. 


163 


animal is revived into buoyancy and energy. In these ani¬ 
mals, while respiration is low, life is low; and, on the con¬ 
trary, while respiration is active, life is in the same condition. 
A similar relation between the amount of respiration and 
the fulness and activity of life is shown in the various races 
of animals. “ The development of their locomotive powers, 
and the degree of heat maintained in thei r systems, will be 
found peculiarly connected with the activity of respiration.” * 
Those which breathe most are the most vigorous, lively, and 
active, while those which breathe least are the most sluggish, 
stupid, and feeble. 

377. The same law holds good for the different individu¬ 
als of any class, as well as for the various races of animals. 
There is a manifest connection between any man’s fulness 
and energy of life and the development and free use of his 
respiratory organs. Wherever the lungs are imperfect, or 
air insufficiently supplied, there is a lower life, a feebler 
power of locomotion, less muscular energy, a duller nervous 
system, a more inactive brain. 

378. These effects are not always noticed and referred to 
their true causes, yet they are none the less certain. In 
persons suffering from consumption, the lungs are more or 
less filled with tubercles and abscesses; the air-vessels are, to 
the same extent, closed, so that the air cannot penetrate 
them, and reach the blood, to purify it. These men are not 
well nourished, for want of pure blood, and therefore they 
waste away; their muscles grow thin and weak, and their 
buoyancy of life is extinguished. Their lungs become filled 
more and more as the disease progresses; and, at last, when 
respiration can no longer be carried on with sufficient power 
to effect its due purposes, they sink in death. 

379. Whatever may be the cause that prevents the lungs 
from receiving a full and requisite quantity of air, the result 
is the same — a lower degree of life. Whether the chest be 
originally small in proportion to the size of the body or 


Carpenter’s Comparative Physiology 


164 


PRACTICAL PHYSIOLOGY. 


made so by artificial means, or whether it be encased so as 
to prevent its natural expansion for the admission of air, 
there necessarily follows the same diminution of energy in 
the performance of the function of respiration. 

380. The effect of imperfect respiration upon the blood, 
and upon the energy of life, is the same, whether it come 
from want of room in the lungs to receive the air, or from 
want of oxygen in it. Those who breathe impure and 
corrupted air, and those who live in small and ill-ventilated 
rooms, show the same languor and feebleness, the same want 
of muscular power and buoyancy of spirit, as those who are 
suffering from consumption, or who have deformed or dimin¬ 
utive chests. 

381. The object of sleep is to restore the exhausted ener¬ 
gies, and give us new life for labor in the morning. But 
for want of sufficiency of air, this balmy restorer often fails 
in some measure of fulfilling its purposes; and, in some in¬ 
stances, it comes very far short of it. In small and crowded 
chambers, the sleep is not sound and refreshing, and the 
sleeper awakes in the morning unrefreshed, indisposed to get 
up, and irresolute in regard to labor. 

382. The laborers who slept in the narrow attic of the 
shanty (§§ 361, 362, pp. 156, 157) assured me that they 
awoke in the morning almost as weary as when they went to 
their chamber; they felt no vigor nor elasticity; they were 
not refreshed by their sleep; they felt a slight nausea, and a 
sinking about the heart, and some headache, after they rose; 
and they ran, as soon as possible, out of doors, to breathe 
the fresh air. After being in the open air a while, they re¬ 
covered their comfortable feelings, and then had some appe¬ 
tite for their breakfast. Even then they had not the muscular 
vigor, nor the power for labor, which they would have had 
if they had been well supplied with air during their sleep. 
It is a mistaken economy to give laborers, or others who are 
expected to use their powers, such small lodging apartments. 
I have felt the same languor and sickness after sleeping in 
the cabins of boats, and have seen the passengers rush to the 


RESPIRATION. 


165 


deck in the morning, even in cold and stormy weather, to 
inhale the fresh air, and remove the oppression, and recover 
themselves from the weariness of their night’s lodging. 


CHAPTER XV. 

Crowded Audiences uneasy and impatient. — Children in unventi¬ 
lated School-rooms uneasy and dull. — Deficiency of pure Air de¬ 
preciates, and total Want of it extinguishes Life. — Breathing Car¬ 
bonic Acid Gas. — Drowning. — Breathing impure Air impairs 
Constitution. — Consumption among Females. 

383. A crowded audience in a lecture-room or concert- 
hall, after a while, become weary and uneasy, and indiffer¬ 
ent to the lecture or the music before them, although the one 
may still be as interesting, and the other as exquisite, as in 
the beginning. Their senses grow dull; they neither under¬ 
stand the arguments of the speaker so readily, nor enjoy the 
harmonies of the music so keenly; and yet they are more im¬ 
patient of mistakes and imperfections. Some complain that 
they never return from such assemblies without a headache. 
The weariness, the restlessness, the impatience, and the pain, 
all arise from one and the same cause — the foulness of the 
air. For want of oxygen, the blood is not purified; then 
impure blood is sent to the muscles, and cannot strengthen 
them to support the body; the same is sent to the brain, and 
irritates it, and disturbs the nervous system. 

384. After children have sat in crowded school rooms for 
some time they grow dull and heavy. Their blood is not 
then relieved of its carbon and hydrogen: impure blood is 
sent back to the heart; and thence it is sent again, with all 
its imperfections, to the whole body. The brain, being fed 
with this corrupted and corrupting blood, instead of being 
enlivened, is made inactive and heavy. It then works lan¬ 
guidly, or refuses to work at all. The children become un¬ 
easy, restless, and oftentimes sleepy; they are averse to 



16G 


PRACTICAL PHYSIOLOGY. 


mental labor, for it is difficult for them to fix their attention 
upon their studies; and they are fatigued with the ineffectual 
attempts to learn that which at other times is easy. But the 
moment they are dismissed, they run eagerly from the im¬ 
pure air of the room to the pure atmosphere abroad, and 
then feel a return of life, and even a glow of exhilaration. 

385. Whenever, in these and other ways, the lungs are not 
supplied with a sufficiency of pure air or oxygen, life is de¬ 
preciated, and this depreciation is in proportion to the foul¬ 
ness of the air. If men dwell in rooms that are perfectly air¬ 
tight, so that no fresh air can be admitted, all the oxygen is 
soon consumed, and then their blood can be relieved of no 
more of its burden of dead atoms, and the vital powers, 
not being sustained, sink, and life is as effectually extin¬ 
guished as it would be if they were buried in the water. In 
this manner, one hundred and twenty-three men died in the 
Black Hole of Calcutta.* The difference between the faint¬ 
ness and languor of a crowded room and the death in the 
Black Hole is a difference only in degree, but not in kind; 
and it is only by step after step, in the same course of cor¬ 
rupting atmosphere and depreciating life, that our children 
in the unventilated school-rooms, and our sleepers in the 
small chambers, and our audiences in crowded lecture-rooms, 
might go from the inconvenience they there feel to the 
death from which they shall awake no more. 

386. If breathing air loaded with more than three and a 
half per cent, of carbonic acid gas be injurious, the breath¬ 
ing this gas in its pure state is destructive. This gas is 
heavier than the air, (§ 295, p. 134,) and therefore it falls to 
the bottom of a vessel or room, like water. Hence it is un¬ 
safe for a living creature to go to the bottom of wells and vats 
that contain it. Fire will not burn in this gas. Workmen, 

* One hundred and forty-six persons were shut up in a room, called the 
Black Hole of Calcutta, on the night of the 20th of June, 1756. This room 
was eighteen feet square, and eighteen feet high, “ open only by two windows, 
strongly barred, from which they could scarcely receive the least circulation 
of air." “ At the dawn of day, only twenty-three persons remained alive out 
of one hundred and forty-six." 


RESPIRATION. 


167 


when they wish to enter a well or vat where they suspect 
its presence, first sink a lighted candle down. If it burns, 
there is air, and it is safe for them to descend; but, if the 
candle is extinguished, there is no air but carbonic acid 
gas; they cannot go down in safety. For want of this pre¬ 
caution, some have been suffocated, and even lost their lives. 

387. Probably more have perished from breathing the 
fumes of charcoal than from breathing any other gas. A 
pan of coals is sometimes left burning in a small bed-room, 
which has no open fireplace, while some one sleeps on the bed. 
The gas given out falls to the floor, and fills the bottom of 
the room, rising as fast as it is produced, until it reaches the 
sleeper’s head. At first, he suffers difficulty of breathing, 
violent pulsations of the heart, which are soon followed by a 
partial and almost entire suspension of the respiration and 
of the circulation of the blood. Then the organs of sense 
lose their power, the sensibility is destroyed, the prostration 
is extreme, and the want of power of motion so complete 
that the sufferer seems dead. If removed, he may possibly 
be restored ; but, if he remains in this gas, destruction of life 
follows as surely as if the sleeper were overwhelmed with 
water. 

388. Drowning produces death, not, as is commonly sup¬ 
posed, by filling the lungs with water, but because the water 
prevents the access of air to the respiratory organs, and the 
sufferer dies from suffocation. 

389. The effects of limited respiration, and of breathing 
impure air, have thus far been considered only in the imme¬ 
diate depreciation of life, or the production of death, by the 
mere deficiency of pure, well-oxygenated air. But often 
injurious and even fatal consequences afterward come. 
Some of the survivors of the Black Hole were seized with 
putrid fever, and subsequently died. Those who breathe 
charcoal gas are for some time drowsy, and are apt to fall 
into a deep sleep, or lethargy, from which it is difficult to 
rouse them; and those who live in close rooms have less 
mental and bodily activity, less sprightliness and energy, 




168 


PRACTICAL PHYSIOLOGY. 


less power to sustain themselves under the exposures of life, 
and less strength to resist the causes or the attacks of 
disease. 

390. Consumption is more frequent among females than 
males. The deaths in Massachusetts for the registered years 
of 1845-50, from this disease, were—males, 5549 ; females, 
9066. This shows the liability of women to this disease to 
be sixty-three per cent, greater than that of men. In Eng¬ 
land, for five and a half years, the deaths from this cause 
were — males, 141,905; females, 161,932. This shows an 
excess of nearly fourteen (13.8) per cent, of females over 
the males. Mr. Farr, in his letter to the registrar-general, 
says, “ The higher mortality of English women by consump¬ 
tion may be ascribed partly to the in-door life which they 
lead, and partly to the compression preventing the expansion 
of the chest, by costume. In both ways, they are deprived 
of free draughts of vital air, and the altered blood deposits 
tuberculous matter, with a fatal, unnatural facility.” * 


CHAPTER XVI. 

Lower Animals can bear Privation of Air longer than higher. — 
Some Men, by Practice, can bear this longer than others. — All 
Animals need Air.—Air covers all the Earth. — Animals con¬ 
sume Oxygen, and give out Carbonic Acid Gas. — Vegetables use 
Carbonic Acid Gas, and give out Oxygen. 

391. If a mouse or rabbit be placed in the exhausted 
receiver of an air-pump, it will die in less than a minute; 
and a bird, which needs more air and that more frequently, 
could not survive this privation more than half a minute. 
But the lower animals, which have less energy of life, endure 
this much longer. Reptiles, serpents, frogs, &c., will live a 
considerable time in a vacuum, or in such gases as cannot 


Registrar-General’s Report, 1840, p, 72. 



RESPIRATION. 


169 


be respired; a tortoise lived twenty-four to thirty-six hours, 
and frogs lived near an hour when placed in oil, while in¬ 
sects died immediately, if placed in the same fluid. Fishes 
die if the water be boiled and the air excluded; yet gold 
fishes have lived in water thus prepared one hour and forty 
minutes. 

392. But if a man be deprived of air, or of the power of 
admitting it to the chest, the circulation of his blood will 
generally cease within ten minutes, and his power of motion 
within five, often within three minutes. Yet some men, by 
long practice, acquire a power of suspending their breath for 
this period, without suffering any apparent loss of power. 
The divers of Ceylon are in the habit of remaining under 
water three, four, or even five minutes, in search of pearls; 
and, when they come up, they seem wearied, but not ex¬ 
hausted.* 

393. This necessity of good air is imposed upon all the 
animated creation, though in an unequal degree. Yet every 
animal, the highest and the lowest, the man and the worm, 
and all intermediate grades of creatures, must sustain life 
by their breath. All of these, from the first to the last mo¬ 
ment of their existence, are continually absorbing and con¬ 
suming the life-giving oxygen of the air, and sending back 
in its stead the poisonous carbonic acid gas. 

394. The air covers the whole globe, and reaches to forty- 
five or fifty miles from it. It is so subtile, that it penetrates 
the smallest crevice ; and, if not excluded by other matter, it 
fills all space within forty-five or fifty miles of the earth. 
Yet, abundant as this air is, it might be feared that the respi¬ 
ration of so many millions of creatures, carried on for thou¬ 
sands of years since the world began, would consume all its 
oxygen, and leave nothing but nitrogen, and carbonic acid 
gas, and vapor, in its place. 

395. To one who looks no farther into the order of na» 
ture, this, perhaps, might be a reasonable fear. But % 

* Carpenter’s Physiology, p, 393, 

15 


170 


PRACTICAL PHYSIOLOGY. 


more thorough examination of the plans of the benevolent 
Author of all things, shows that there is no natural want 
without a due supply. And if that want be permanent, the 
means of gratifying it are equally so, and coextensive with it. 
The works of the Creator are all arranged in infinite wisdom. 
There is no deficiency — there is no want of harmony. 
The oxygen, which is so continually and universally con¬ 
sumed by the animal creation, is restored by agents equally 
universal and permanent. 

396. Animals and vegetables meet each other's wants , 
and supply each other's necessities. The animal uses oxy¬ 
gen, and gives out carbonic acid gas; while, on the other 
hand, the plant uses carbonic acid gas, and gives out oxygen. 
The vegetables, like animals, breathe air; but, unlike them, 
they breathe it for the carbonic acid, and not for the oxygen. 
Through the leaves of some, which are provided with them, 
and through the bark of others, the carbonic acid is absorbed 
from the air, and then, within this vegetable respiratory ap¬ 
paratus, it is decomposed — the carbon is retained to nourish 
the plant, while the oxygen is thrown out for the use of the 
animated creation. Thus the equilibrium is maintained; 
and, as long as both live together, there need be no fear of 
their suffering for want of air suited to their necessities. 

397. This process of respiration of vegetables is con¬ 
ducted only in the presence of light. In its absence, in 
darkness, precisely the reverse takes place, and the vegetable 
respiration is similar to that of animals — oxygen is ab¬ 
sorbed, and carbonic acid given out. 

398. Plants, then, as they aid animal respiration when 
they have the light of the sun, are proper and healthy accom¬ 
paniments of any inhabited room in the daytime. But, on 
the other hand, as, in darkness, they consume the oxygen 
that animal respiration needs, they are unhealthy and inju¬ 
rious to be kept in rooms which are occupied in the night 
for sleeping or other purposes. 


ANIMAL HEAT. 


171 


PART IV. 
ANIMAL HEAT. 


CHAPTER i. 

Internal Heat of living Bodies usually greater than the Heat of sur¬ 
rounding dead Matter. — Whales and Porpoises in the Arctic 
Ocean as warm as at the Equator. — Man’s Heat does not vary 
in Extremes of Temperature. — Blagden’s Experiment. — Natural 
Tendency to Equilibrium of Heat in all dead Matter. — Living 
Matter sustains its own Heat. 

399. It is easy to see that the temperature of most ani¬ 
mals is higher than the surrounding medium. Our own 
bodies are usually warmer than the air about us. In winter, 
especially, when water freezes and the air is colder than ice, 
this fact is to be noticed. If we then lay our hands upon 
the body of a horse or a kitten, or upon our own flesh, we 
find them to be warmer than the air. If we take ice into 
our hands, it melts, from the natural heat of our flesh; and 
yet this flesh is not cooled down to the coldness of ice, and, 
although it loses a little heat while it is in contact with the 
ice, it soon recovers it after the ice is taken away. 

400. The porpoise and the whale dwell under the ice, in 
the waters of the Northern Ocean. Above them, the air may 
be cooled down to 50° below freezing point; the temperature 
of the ice is at least as low as 32°, and the water is nearly 
as cold, and yet they are warm. Their temperature is sus¬ 
tained at about 100°, as high as that of other animals of the 
same kind, in the burning regions of the equator. 

401. Man dwells in all climates; he finds a home in 



172 


PRACTICAL PHYSIOLOGY. 


every country, from the equator almost to the poles. Under 
the equator, the temperature of the atmosphere is elevated to 
100°, bodies exposed to the sun are heated to 130°, and the 
inhabitants are there subjected to a perpetual heat. In the 
northern regions, Captain Parry found the thermometer as 
low as 55° below zero; and Captain Back found it 15° lower 
*han this, or 70° below zero. These were 87° and 102° below 
freezing point. And yet, in these extremes of external tem¬ 
perature, the internal heat of the human body varies very 
little. There are greater differences than even this. In 
France, some bakers entered their ovens heated up to 278°, 
or 66° warmer than boiling water, without increasing their 
own heat. And some philosophers of London tried the ex¬ 
periment, to ascertain how great heat could be borne without 
injuring or increasing the temperature of the living body. 

402. Sir Charles Blagden entered a room, prepared for 
the purpose, in which the thermometer stood at 260°; and 
there he staid for eight minutes. Eggs were put into the 
same room, and were soon roasted quite hard. “ Beefsteak 
was not only dressed, but almost dry.” And yet here, in 
this great heat, in which water boiled and meat was cooked, 
the thermometer, when placed under the tongue, was raised 
only to 100°, two degrees above the usual standard. There 
have been many other experiments and observations of this 
kind, which show the same principle — that the heat of the 
living body does not change, or changes very slightly, with 
the temperature of the air or water which surrounds it. A 
dyer will hold his hands in water at the temperature of 130°, 
and the ice-cutter has his hands in contact with ice at 32°; 
and, in both instances, the temperature of the body is about 
the same, neither raised in one case, nor depressed in the 
other, materially. 

403. There is a natural and almost universal tendency to 
equilibrium of heat. When a warm and a cold dead body are 
brought in contact, their heat is shared in common between 
them. One loses, and the other gains, heat, so that in a 


ANIMAL HEAT. 


173 


short period, they have equal temperatures; neither i 3 
warmer or colder than the other. 

404. If a piece of wood or of dead flesh be put into hot, or 
even boiling water, it soon is as warm as the fluid. If it be 
put into cold water or snow, it soon becomes as cold as that. 
If ice be put into hot water, it receives a part of the heat of 
the fluid. It first melts, and its water is then warmed up to 
the temperature of the original water; while this, losing its 
heat, is cooled down to the temperature of the water from 
the ice, and, finally, both have the same degree of heat. 
The same effect is seen when any substances are placed in 
air of different temperature. When the atmosphere is at 32°, 
water freezes, and solids become as cold as ice. On the 
other hand, water boiled, and the eggs and the beef were 
heated up to the temperature of the room which Sir Charles 
Blagden entered. 

405. But it is not so with living beings. Their tempera¬ 
ture does not follow that of the surrounding and contiguous 
objects. The temperature of the warm-blooded animals, — 
of man, horses, and birds, for instance, — scarcely varies 
with any extremes of cold or heat to which they may be ex¬ 
posed. The usual temperature of man is 98°. If a ther¬ 
mometer be placed in his mouth, in the East Indies or in 
the arctic regions, it will be found the same. The body 
sustains its own temperature in the cold medium, and is no 
warmer in the heated room. 

406. If this were not so, if the temperature of our bodies 
should follow that of the surrounding medium, the most fatal 
consequences would ensue. The blood and the flesh would 
be frozen, and all our motions stayed, and life extinguished, 
in the severe weather of winter, even in the temperate cli¬ 
mates; and, on the other hand, the fatty portions of our 
frame would sometimes, in the tropical climates, melt, and 
the blood would boil in such experiments as Blagden tried. 

15 * 


J 74 


PRACTICAL PHYSIOLOGY. 


CHAPTER II. 

Law of Equilibrium of Heat different in Regard to living and dead 
Matter. — Animals maintain their own Temperature, and give 
Heat to other Bodies, — Animal Heat generated within.— Warm 
and cold blooded Animals. — Power of sustaining Heat varies 
with respiratory Apparatus.—Fishes breathe by Gills, and have 
little Heat. — Whales breathe by Lungs, and have much Heat. — 
Animals have internal Apparatus for generating Heat. 

407. Beside this maintenance of its own warmth, the 
living animal body is continually giving out heat to other 
substances which are cooler than itself; and yet it does not 
apparently lose its own heat; at least its temperature remains 
undiminished. If we hold a piece of ice in our hand, it is 
melted, but the hand is not much cooled; or, if cooled, it 
soon regains its heat after being separated from the ice. But, 
if we place the ice upon a piece of iron heated to the tem¬ 
perature of the hand, the ice melts there, as in the other 
case, and the iron is cooled down to a lower temperature, and 
the watBr of the ice is raised to the same degree. The ice 
cools the iron, and the iron warms the water of the ice; and 
then the temperature of both remains the same, until some 
external influence changes it. 

408. Here, then, is a manifest difference in the law that 
governs the heat of living and that of dead substances. One 
class seems to have heat only in common with contiguous 
and surrounding objects. If they are warm, the dead matter 
becomes warm; if they are cold, this is cooled to the same 
degree. It neither warms itself nor cools itself, but depends 
upon others for its heat. But the living body is neither 
cooled nor heated materially by surrounding matters. Its 
own heat seems to be independent of them. 

409. Our heat is not borrowed from external objects; 
certainly not from the atmosphere, for we have seen that 
the human bodies are warm when the air is extremely cold; 
nor from the sun or fire, for we are warm in the absence of 


ANIMAL HEAT. 


175 


both. Nor is our heat derived from clothing, for this has no 
active power of giving heat — it has no warmth in itself; it 
only tends to prevent changes of temperature. If we wrap a 
piece of dead flesh in flannel, it is not warmed; it remains 
the same as before. If, in the winter, this flesh be heated 
by fire, the flannel wrapped about it keeps it warm. If, in 
summer, we put ice in flannel, it prevents the melting. 
Clothing, then, only prevents the passage of heat. It keeps 
a warm body warm, and a cool body cool; but it creates 
and gives no heat. If, then, animal heat is not given from 
without, it must originate within the body. There must be 
some internal means or apparatus by which we and other 
living beings create and sustain our temperature. 

410. There are two grand classes of animals, divided ac¬ 
cording to their temperature. One is called the warm¬ 
blooded, and includes man, birds, quadrupeds, &,c. Their 
heat is ever of the same degree, and does not vary with the 
temperature of the atmosphere or the water in which they 
live. The other class is called cold-blooded , and includes 
snakes, oysters, fishes, worms, toads, turtles, &c. Their heat 
is but little higher than that of the medium in which they live. 
The earth-worm, leech, and shell-fish are usually 1J° warmer 
than the air, or earth, or water which surrounds them. 
Fishes are 2° to 5° warmer than the water. Reptiles, frogs, 
lizards, have a still higher heat relative to the air or water, 
yet not so high and permanent as that of the warm-blooded 
animals. 

411. There is, in these two great classes, a great differ¬ 
ence of power of maintaining their own heat. Man main¬ 
tains his usual temperature in the midst of air varying 330° 
from extreme heat to extreme cold ; and therefore he may be 
at least 160° warmer, or 160° cooler, than the surrounding 
medium; while a fish is only 2° or 3° warmer or cooler than 
the water in which it lives. It is natural, then, to ask, 
What is the difference in the structure of these classes, from 
which arises this difference of internal heat 1 On examina¬ 
tion, we find that the principal difference that runs through 


176 


PRACTICAL PHYSIOLOGY. 


the whole of these classes is in the apparatus of respiration. 
The warm-blooded animals breathe more and purer air than 
the cold-blooded. Fishes breathe only by gills, and receive 
only the little air that is in the water, and they are cold; 
we breathe with full lungs, and receive a more plentiful sup¬ 
ply of air, and are heated to 98° ; while birds have the largest 
means of respiration, and breathe the purest air, and are 
consequently from 2° to 13° warmer than even man. Insects 
have generally larger means of respiration, and a higher 
temperature. 

412. There is a remarkable difference, in this respect, 
among the inhabitants of the sea. Fishes — such as the pike, 
cod, haddock, sturgeon, smelt, &,c. — which breathe by gills 
are dependent solely upon the air in the water. They can 
therefore neither obtain nor consume more than a very small 
portion of air, and consequently they are cold. On the con¬ 
trary, whales, porpoises, and dolphins breathe by lungs. 
They rise to the surface of the water, and inhale the free air 
above it. They find this abundant, and consume it plenti¬ 
fully, and consequently their temperature is about 100°, and 
independent of the heat of the water. It is neither depressed 
in winter nor raised in summer. They are therefore classed 
with the warm-blooded animals. 

413. In order to maintain this heat within the animal 
body, constantly and independently of the influence of sur¬ 
rounding and contiguous matters, two conditions are neces¬ 
sary : 1st, each animal must possess some internal appara¬ 
tus for generating or creating this heat; 2d, the skin, or the 
external covering, must be endowed with such a power of 
regulating the transmission of heat, that it may prevent its 
too rapid passage out in winter, or when the air is colder 
than the body, and also its passage into the body in summer 
or when the air is warmer than the body. 


ANIMAL HEAT. 


177 


CHAPTER III. 

Latent and sensible Heat. — Heat applied to Ice forms Water, and 
to Water, makes Steam. 

414. The warm-blooded animals breathe more than the 
cold-blooded. The same difference prevails among the sub¬ 
divisions of these classes, for the warmest kinds breathe more 
than the coldest. It would seem, then, that the internal heat 
arises out of, or is in some way connected with, respiration. 
And this we find to be strictly true, upon examination of the 
nature and properties of the elements of air, and of the 
chemical effects produced by this gas upon the blood and 
particles of the animal body. 

415. When ice is melted and changed to water, it is easy 
to see that heat is given to it, and absorbed by it. The heat 
necessary to produce this change has united with the ice, 
and both together have become water. Again, if much more 
heat is applied to this water, it boils and is changed to vapor 
or steam. By continuance of the same process that pro¬ 
duced the first change, the second one is produced; and, by 
the union of heat with water, steam is formed. It is obvious 
that steam contains more heat than water, and water more 
heat than ice. Heat added to ice produces water, and heat 
added to water produces steam; and, in both cases, most of 
the heat becomes latent or hidden in the new substance. 
If, now, we reverse the process, and return the steam back 
to water, heat must be given out. Just so much is given out 
as was originally required to convert the water into steam. 
If we continue this process further, and change the water to 
ice, there must be a further discharge of heat; and as much 
heat will be given out, in this process of freezing the water, 
as was before required to melt the ice. 

416. There is a general law of matter, that rare or light 
substances require more heat than dense or heavy matters. 
Liquids commonly require more heat than solids, and gases 
moie than liquids, to keep them in their respective states' 


178 


PRACTICAL PHYSIOLOGY. 


and abstracting heat renders them more solid, while adding 
heat renders them more fluid. By a great reduction of tem¬ 
perature, airs or gases can be condensed to fluids; and, 
during this change, heat is given out. 

417. The apparent heat of a body, as measured by the 
thermometer, or as perceived by the touch, is not always an 
exact measurement of the quantity of heat in that body. If, 
for instance, we mix a pound of water heated to 100°, with 
a pound of spermaceti oil at 50°, it might be supposed that 
the temperature of the mixture would be 75°, the exact me¬ 
dium between them. This would be the case, if each of 
these bodies were raised to the same temperature by the 
same quantity of heat. But the temperature of the mixture 
is actually 83J°. If, again, the experiment be reversed, and 
water at 50°, and oil at 100°, be mixed, the result is a tem¬ 
perature of 66§°. Instead of the warmest substance losing 
25°, and the coolest gaining as much heat, we find that, in 
the first instance, the water loses only 16§°, while the oil 
gains 33£°; and, in the other case, the oil loses 33£°, and 
the water gains 16§°. That is, the quantity of heat that will 
warm water 16J° will warm oil 33£°; or, the water requires 
twice as much heat as oil does, to raise it to any definite 
temperature. It will, then, be clearly understood, that the 
same substance has different quantities of heat in its different 
states; and also that one substance requires more heat than 
another to give it the same apparent heat. 

418. The burning of wood and all other fuel shows 
both of these principles. Oxygen exists in the air in the 
state of gas. (§ 292, p. 133.) When wood or coal is heated, 
this oxygen combines with the carbon of the fuel, and forms 
carbonic acid. In this process, the oxygen enters into a 
new state, and becomes a part of a compound more dense 
than it was before. On two accounts it loses heat; 1st. 
oxygen has greater capacity for, or holds more, heat than 
carbonic acid gas, and therefore, when this new gas is 
formed, the surplus heat, or that excess of heat which oxygen 
can hold over that which the other gas can hold, must be 
given out; 2d, the oxygen is in a denser state when it 



ANIMAL HEAT. 


179 


composes a part of the carbonic acid gas than when it ia 
pure and uncombined, and therefore holds less heat, (§ 416, p. 
177,) and must give out some when it enters the compound. 
From both of these causes, heat is derived from fire of every 
kind. Whatever may be the theory or explanation, the fact 
is evident, that heat is evolved from the union of oxygen 
with fuel — carbon or hydrogen. This is what we call com¬ 
bustion or jire. The amount of heat thrown out from this 
union or combustion is always in proportion to the amount 
of material consumed. A pound of wood in a solid block 
gives out the same quantity of heat, in burning slowly, as a 
pound of shavings of the same wood, in burning rapidly. 

419. Upon these principles, it will now be easy to under¬ 
stand how the warmth of the animal body is obtained. The 
particles of our flesh are continually changing. (§§ 242—244, 
pp. Ill, 112.) The old ones are going away, and new ones 
taking their places. The principal components of these old 
particles are carbon, nitrogen, and hydrogen. (§ 290, p. 132.) 
When the air is received into the lungs, and brought into 
contact with the old and verfous blood, it is decomposed, or 
divided into its two elements; the oxygen is separated from 
the nitrogen, and united with the blood. (§ 297, p. 135.) 
The blood, at the same time, throws out into the air carbonic 
acid gas and vapor, (§§ 297, 303, pp. 135, 137;) and then, 
being relieved of these impurities, it is returned to the heart, 
and thence it is circulated throughout the body, carrying 
the newly-acquired oxygen with it. 

420. It was once generally believed, and it is now sup¬ 
posed by many, that the oxygen does not enter the blood, 
but that these dead particles are brought unchanged to the 
lungs, and there the carbon and the hydrogen, meeting the 
oxygen, combine with it, and form carbonic acid gas and 
water, which are given out with the returning air. 

421. But it is now, with better reason, supposed, that 
the oxygen of the air enters the minute arteries in the lungs, 
and is there mingled with the blood. It is then carried 
with this blood to the heart, and thence sent through the ar¬ 
teries all over the body. When this blood, and the oxygen 


180 


PRACTICAL PHYSIOLOGY. 


which it carries along with it, reach the minute arteries and 
the capillaries, where the work of nutrition is carried on, 
the interchange of the old for the new particles of flesh takes 
place. The old — those which have finished their work and 
are dead — give way, and the new ones, fresh with living 
vigor, take their stations and perform their part in the work 
of life. As these old and dead atoms of flesh pass from their 
stations to the vessels, the oxygen in the blood meets them, 
and they unite together and form new compounds. The 
union of the oxygen with the carbon produces carbonic acid, 
and its union with hydrogen produces water. These unions 
take place in the same manner, and the same results follow, 
as when the carbon.of the wood in the fireplace, and the 
hydrogen of the gas lamp, unite with oxygen. The carbon 
and the hydrogen are burned, fire is produced, and heat is 
evolved; the carbonic acid and the water are then carried 
through the veins to the heart and the lungs, and the heat is 
left in the textures of the living body. During this process, 
precisely the same amount of heat is given out from this in¬ 
ternal fire — this slow combustion of the wasted particles of 
flesh—as would result from the combustion of the same 
amount of fuel, carbon, and hydrogen elsewhere. 


CHAPTER IV. 

Exercise increases Combustion of Carbon and Evolution of Heat.— 
Whatever increases Flow of Blood increases Heat, and whatever 
diminishes Flow of Blood lessens Heat. — Oxygen and Fuel neces¬ 
sary to support internal Fire. — Whatever interrupts Supply of 
Oxygen or Air to Lungs, prevents Development of Heat. — Tight- 
Lacing lessens Heat. — Bad Air — foul Air — lessen it. — Food 
supplies Fuel. — Well-fed warmer than the Ill-fed. — Alcohol does 
not increase the Heat of the Body. — Meat supplies more Fuel 
than Bread. — More Meat eaten in cold than in warm Weather. 

422 . This work of interchange of particles, and of burn¬ 
ing the old flesh, is carried on throughout the whole body j 



ANIMAL HEAT. 


181 


consequently, every part of the body is warmed. The more 
rapid is the circulation and the more frequent are the 
changes of living for dead particles, the more carbon and 
hydrogen are burnt, and the greater is the heat given out. 
Whatever increases the interchange of particles, the work of 
absorption and nutrition, and consequently the flow of blood, 
increases the internal fire and the evolution of heat. Motion 
is attended with greater waste of particles, and, of course, 
with greater absorption of carbon and hydrogen, (§ 127, p. 
61,) and greater development of heat. Labor, therefore, 
warms the body, and, if violent, may heat it uncomfortably. 
The watchman keeps himself warm with exercise, and the 
passenger leaves his vehicle to warm his feet with running. 
The hardy laborer heats himself with his exercise, and sits 
down quietly to cool his body. 

423. On the contrary, whatever interrupts the circulation 
and the interchange of particles prevents the development of 
heat. If we bind up the arm or finger with a tight cord, 
and prevent the flow of the blood through it, the limb be¬ 
comes cold. It is a common and a true observation, among 
shoemakers, that a loose boot is warmer in winter than a 
tight one, because the latter presses upon the blood-vessels, 
and interrupts the full flow of blood. So we find, if one 
side or one limb be palsied, that side or that limb becomes 
cold, for the same reason. 

424. This animal heat then, is sustained by the combus¬ 
tion of the dead atoms of the flesh in all the parts of our 
frames where the blood circulates. In order to maintain 
this combustion, the same things are requisite that are 
needed to support fire elsewhere; these are fuel and air. 
To deprive the body of either would be as fatal to its internal 
heat as taking away the fuel or the air would be to the fire 
of the stove. As the wood in the fireplace burns by aid of 
the' oxygen which it derives from the air, and as this fire 
burns freely in proportion to the quantity of air which it 
receives, so the internal fire of the animal body, deriving its 
oxygen from the air, burns in proportion to the fulness of its 

16 


182 PRACTICAL PHYSIOLOGY. 

supply. Consequently, whatever impedes the flow of air into 
the lungs, and its access to the blood, must so far prevent 
the development of internal heat, as certainly as any inter¬ 
ruption of the draught or diminution of air would lessen the 
fire and the heat of the fireplace. 

425. Whatever, then, restricts the expansion of the chest, 
or limits the capacity of the lungs for the admission of air,— 
any pressure of clothing without that prevents the motions 
of the ribs or the diaphragm, or any disease of the lungs that 
closes the air-cells within, — any of these obstructions, by 
lessening the amount of oxygen that the blood receives, 
diminishes the combustion of the atoms of dead flesh and 
the evolution of the internal heat, as certainly as shutting 
the draught of a stove would lower or extinguish its fire. For 
this reason, asthmatic persons, and those whose air-cells are 
partially closed with disease, are only partially warmed, and 
cannot endure so severe a cold as men in health. A poor 
woman, whom I saw sick with consumption in a very cold 
room, was frozen to death, one night, in her bed, in the 
winter of 1830, while some other women, who slept in the 
same room, and under the same quantity of clothing, awoke 
in vigor, though suffering with cold. 

426. Nothing but oxygen can support this internal com¬ 
bustion of fuel. We must not only receive a sufficiency of 
air into the lungs, but that air must contain its due* propor¬ 
tion of this gas. If, then, the air contains less than the due 
quantity, if it has been breathed over, and its oxygen has 
been consumed, or if, in consequence of mixture with other 
gases, the forty inches which we inhale contains less than 
twenty per cent, of oxygen, then the internal combustion is 
impeded, heat is sparingly evolved, and those who breathe 
this impure or weakened air are comparatively cool. After 
a crowd has been long in session in a close hall, or children 
in an unventilated school-room, in winter, they begin to 
complain of being cold. Notwithstanding the fire may glow 
in the stove, and the thermometer indicate no reduction of 
temperature, still, for want of oxygen in the vitiated air, the 


ANIMAL HEAT. 


JS3 


fire burns languidly in the bodies of the people, the} are not 
well warmed, and their sensations persuade them that the 
room is growing cooler. 

427. The narrow-chested are colder than the broad- 
chested ; the tight-bound, than the loosely-dressed ; and those 
who breathe the impure air of close and unventilated rooms, 
than those who breathe the free air of the fields. The former 
need more external protection of houses or clothing, or more 
outward heat from fires, than the others. A free expansion 
of the chest, with a good supply of pure air, is, therefore, an 
economy of clothing and of fuel. When the air is dense 
and heavy, as when cooled, it contains a greater weight of 
oxygen to the cubic inch, than when it is rare and light, as 
when heated. We therefore breathe more oxygen in winter 
than in summer, and the fire, consequently, burns most ac¬ 
tively when it is the most needed. 

428. Fuel, as well as air, is necessary to keep up this 
internal combustion in the animal body. This is supplied by 
the atoms of wasted flesh that have died in the various tex¬ 
tures, and are ready to be burned or combine with oxygen, and 
need to be carried away. The combustible matters of the 
flesh — its carbon and hydrogen — are originally supplied by 
the food that contains the same materials. These elements 
of the food, being converted first into chyle, then into blood, 
and next into flesh, are at last burnt by their union with 
oxygen, and carried out through the veins and the lungs. 
As the food is the only source from which this fuel is sup¬ 
plied, of course, all other things being equal, the internal 
fire must burn, and the body be warmed, in proportion to the 
amount of carbon and hydrogen which is eaten, and incor¬ 
porated into and becomes a part of the textures. 

429. The well-fed and well-nourished, — those who live 
upon good and generous food, — having a better supply of 
fuel, are therefore better warmed than the hungry, or those 
who live upon a poor and meagre diet. The traveller who 
has been long exposed to the severe weather without eating, 
in winter, complains that he is both hungry and cold. His 


184 


PRACTICAL PHYSIOLOGY. 


hunger and his low temperature may seem to him to be mere¬ 
ly coincident circumstances, accidentally coming together; 
but, in truth, one is the cause of the other. For want of 
food, his body is not supplied with fuel, afld its internal fire 
burns feebly, and therefore does not warm him. One of the 
best means of protection against the effects of exposure to 
the cold air of winter is proper nutriment. 

439. Alcoholic spirit is sometimes taken for this purpose, 
but with a mistaken view of its effects upon the heat of the 
body. It stimulates the stomach, excites the nervous system, 
and quickens the action of the heart, and the flow of the 
blood. It supplies to the flame carbon and hydrogen, the 
most combustible of materials; but these soon burn out, and 
their fire is then exhausted, and the body is afterward cooler 
than it otherwise would have been. Food, alone, can sustain 
a permanent fire. Two travellers met, in a very cold day of 
January, 1810, at a tavern in Groton, Massachusetts. One 
of them called for a mug of hot flip, and advised the other to 
do the same; for, he said, “ When I am going out in the 
cold, I always drink hot spirit.” The other refused, but 
said, “ When I am going out in the cold, T eat a good din¬ 
ner.” The temperate traveller acted from his own experi¬ 
ence, and also, without knowing it, upon the truest physio¬ 
logical principles. 

431. Flesh, containing more carbon and hydrogen, sup¬ 
plies more fuel to the fire than vegetable matter. Meat, 
therefore, warms a man more than bread, and we eat it more 
freely in the winter than in the summer. For this reason, 
the coachman, the sailor, and the teamster, who are exposed 
to the coldest air abroad, need more meat than the mechan¬ 
ics, who work in warm shops, or those persons whose life and 
occupations are in warm houses. In the northern regions, 
where winter reigns with great severity, there is a more rapid 
loss of heat through the skin, and of course a necessity of 
creating more within the body, than in the warmer re¬ 
gions, at and near the equator. To keep the body warm, 
there must be more fuel, or food containing more carbon and 


ANIMAL IIEAT. 


185 


hydrogen, in the cold than in the hot climate. Nature sup¬ 
plies this necessity by the difference of food, and of digestion, 
of the inhabitants of these diverse regions. The principal 
diet of the people within the torrid zone is of vegetable ori¬ 
gin, while the inhabitant of the frigid zone lives mostly 
upon flesh; and the people who inhabit the countries in the 
temperate zones, between these, have a mixed diet, in which 
the meat predominates as they approach the arctic circle, 
and the vegetable predominates towards the tropics. 


CHAPTER V. 

Other Influences may affect Supply of Heat.— Some Diseases in¬ 
crease, some diminish it. — Fatigue and Exhaustion lessen Evo¬ 
lution of Heat.— Infants and old Men have less Heat. — Less 
Heat evolved in Sleep. — Carbon consumed and Heat evolved in a 
Day. — Heat must be carried out of the Body through the Skin.— 
Evaporation of Perspiration carries off Heat. — Greater Internal 
Fire in cold than in warm Climates. — Winter and Summer Con¬ 
stitution. — Animals cool more rapidly in Summer than Winter at 
same Temperature. 

432. This chemical explanation of the origin of animal 
heat is shown at length in Liebig’s Animal Chemistry. 
There are doubtless other influences that affect the develop¬ 
ment of internal heat, beside the supply of carbon, hydrogen, 
and pure air. It is thought, by some philosophers, that the 
combustion of the carbon and the hydrogen in the living body 
does not account for all the heat which is known to exist in 
it, and that the nerves, in some way or other, add to the sum 
of heat: but in what way, or to what extent, is not easily 
explained. Further discoveries in chemistry may throw new 
light upon the subject of animal heat. 

433. Even when the body is well supplied with both good 
food and pure air, there is not an equal development of heat 
in all states of the system. In some diseases, such as fever, 
inflammations, &c., the heart beats quicker, and the flow of 

16* 



186 


PRACTICAL PHYSIOLOGY. 


blood is more rapid than natural, and there is a greater pro¬ 
duction of heat. But in some other diseases, as asthma, 
cholera, &c., there is, on the contrary, a greater coldness 
The internal warmth is affected by the condition of the 
nervous system, by excitements and depressions, by the 
emotions, the passions, and the states of mind. One is burn¬ 
ing with anger or with love. The exciting and the ardent 
passions quicken the flow of the blood, and increase the 
internal heat, while the depressing passions diminish it. 
Cheerfulness and merriment promote the evolution of heat, 
while fear, sorrow, and despondency impede it. 

434. Fatigue, exhaustion, hunger, night-watching, sleep¬ 
lessness, indigestion, or any thing that depresses the system 
and diminishes the energies of life, lessens the production of 
heat, and the power of resisting cold. In this condition, one 
cannot bear exposure to a low temperature as well as when 
he is fresh and vigorous. He is then more liable to take 
cold. Visiting a friend, a public officer, in the afternoon of 
a pleasant day of March, I found him shivering over a fire, 
though otherwise in good health. He said that he had been 
out to walk, and was chilled. It was a warm day, and other 
men complained of the heat; but they were vigorous, for 
they had been refreshed by their night’s sleep; but he, hav¬ 
ing an important report to finish, had sat up, and labored 
upon it with all his mental energy, until two o’clock in the 
morning; then, being exhausted, he retired, but awoke in 
the morning still fatigued and unrefreshed; consequently, he 
had not sufficient power to maintain his proper heat, even in 
a temperature which was comfortably warm to men in the 
enjoyment of their usual vigor. 

435. In the different periods of life, there is a difference 
of power of producing internal heat. It is more feeble in 
infancy and in old age than in the vigorous years of youth 
and manhood. Dr. Edwards exposed some young and old 
sparrows to a temperature of 64° with the same amount of 
protection. At the end of a definite period, the young were 
cooled down to 66°, while the older birds maintained their 


ANIMAL HEAT. 


187 


temperature at 102°. Full-grown magpies lost 5° of heat in 
the same atmosphere, and in the same time that young birds 
of the same species lost 25° of heat. The same law applies 
to children and men. Infants and old men cannot, therefore, 
endure the cold so well as men of middle life, and need more 
careful protection of clothing when exposed. 

436. “ The state of natural sleep is in general accompa¬ 
nied by a diminution of the power of producing heat.” The 
body is then more susceptible of the influence of cold. Thus 
the consumptive woman (§ 425, p. 182) was frozen during 
her sleep. Night travellers are in much more danger of 
suffering from the cold if they allow themselves to sleep 
than if they keep awake. 

437. The amount of heat given out from the combustion 
of a definite quantity of carbon or hydrogen, or the union 
of either of these with oxygen, has been determined by 
experiments. It is found, also, to be the same wherever this 
combustion takes place, whether in or out of the living body, 
and whether it happens rapidly and with a flame, as in the fire 
of a furnace, or slowly, atom by atom, as in the textures of 
the animal body. If, then, we can ascertain the amount 
of these elements which are consumed in the living system, 
and in any given time, we can determine the amount of heat 
which will be then evolved. 

438. In the course of twenty-four hours, there are, on 
an average, 13.9 ounces of carbon converted into carbonic 
acid gas, and given out from the lungs of every adult in 
good health. Every ounce of carbon, during the process of 
combustion, evolves as much heat as would raise 78.15 
ounces, or almost five pounds, of water, at 32°, or the tem¬ 
perature of ice, to 212°, or the boiling point; and, conse¬ 
quently, the 13.9 ounces of carbon, which are consumed 
in the human body daily, must give out heat enough to raise 
67.9 pounds of water from 32° to boiling heat. So much 
heat is, then, generated within the body of a person of the 
average size and in good health, in the course of each day.* 


Liebig’s Animal Chemistry, Part I. $ V. 


188 


PRACTICAL PHYSIOLOGY. 


The amount of hydrogen consumed is not so easily deter¬ 
mined ; but it is supposed by learned chemists that a great 
proportion of the animal heat is given out by it. 

439. If so much heat be daily added to the body, the 
same amount must be carried off in some way, otherwise it 
will warm the body too much, and cause distress. But it 
does not increase; when the body is at its usual temperature, 
it does not become any warmer, although so much heat is 
continually added to it. This quantity must, then, find its 
way out, through the surface and through the passages. 
Whatever goes from the body, carries some of its heat. 
However cold may be the air which we inhale, it becomes 
warm within the lungs, and is then exhaled at the tempera¬ 
ture of the body. 

440. The skin is the main avenue of the heat outward; 
and through this it is continually passing away, both winter 
and summer. When the air is considerably colder than the 
body, it is very plain to every one that heat goes off by 
transpiration through the outward surface, in order to main¬ 
tain an equilibrium with the surrounding atmosphere; and 
thus the internal temperature does not rise. But when the 
air is as warm as, or even warmer than, the body, this transit 
of heat outward is not so manifest, yet it is equally certain. 

441. The skin not only affords a passage-way for the heat 
to go out, as through any dead substance, but it has an active 
power to furnish the means of carrying off the surplus heat, 
when it would otherwise accumulate in the body. The skin 
is constantly preparing and throwing the perspiration upon 
its surface, where it is usually converted into vapor and ab¬ 
sorbed by the atmosphere. This change of the perspiration 
from a fluid to a gaseous form — from water to vapor — is 
effected by the addition of heat, (§416, p. 177,) which is 
absorbed from the body, and therefore cools it. This perspi¬ 
ration is most abundant in warm weather, when the air can 
absorb the most, and causes the greatest cooling when it 
is most needed. It is a common, and by no means an un¬ 
founded notion, that one is cooled and refreshed, in summer 


ANIMAL HEAT. 


1S9 


by drinking a cup of hot tea. The tea excites the perspira¬ 
tion, which creates the necessity of evaporation; and this is 
done very much at the expense of the heat of the body, which 
is thereby cooled. All the insensible, and most of the sensi¬ 
ble perspiration is converted, on the skin, into vapor ; and, 
by this conversion of liquid into vapor, a large portion of the 
excess of heat is carried out of the body, and the standard 
of the internal temperature is preserved. 

442. This evaporation was very rapid in Sir C. Blagden’s 
experiment, (§ 402, p. 172;) consequently, the temperature 
of his body was kept down to about its usual standard, which 
was 162° below that of the surrounding air which he 
breathed. He received dry air into his lungs heated to 260°, 
but when it went out, it was cooled down nearly to 98°; and, 
when he breathed this air upon his skin, it felt cold, instead 
of warm, as it usually does. 

443. By the beautiful adaptation of Nature’s supply to her 
wants, the animal body is kept cool in the summer and warm 
in the winter. The greater appetite and greater desire for 
animal food, supply more carbon and hydrogen, and the 
density of the air supplies more oxygen, and consequently 
a greater fire is maintained, in the cold season, and in cold 
climates, than in warm seasons, and in hot climates, when 
and where the appetite craves, and the stomach digests, vege¬ 
table diet, which gives less fuel, and the atmosphere affords 
less oxygen for the support of the combustion. 

444. It is this greater supply of internal heat, and the 
lesser cooling by evaporation from the surface, that give us 
what is called the winter constitution; and the diminished 
internal fire, and increased evaporation of the perspired 
fluids, give us the summer constitution. By these means, the 
body is able to endure a greater degree of cold in the 
winter, and in the climate of the polar regions, than in 
the summer, and in the tropical countries; and we can 
bear a greater degree of heat in the summer and in warm 
climates, than in the winter and in cold climates. That 
degree of cold which we bear without discomfort in January, 


190 


PRACTICAL PHYSIOLOGY. 


is almost intolerable, in August. We are sometimes almost 
overcome, at least languid, with the heat of a thawy day of 
February, when the thermometer is no higher than 40°. 
But we are chilled with the air of the same temperature in 
July. For this reason, we need to have our sitting-rooms 
somewhat warmer in the summer than in the winter. An 
ice-house is a sufficiently warm and comfortable place for a 
man to work in while storing ice in the winter, but it is 
chilly and often dangerous to those who enter it in the sum¬ 
mer to take ice away. 

445. To demonstrate how much more rapidly the heat 
passes away, and how much less power of resistance to cold 
the animal body possesses, when it is under the influence 
of its summer, than when under the winter constitution, 
Dr. Edwards, of Paris, took several sparrows from their 
warm rooms, in the month of February, and put them in a 
cage surrounded by ice, where the temperature was, at the 
highest, 32°; after remaining there three hours, they had 
cooled less than 2°. He tried the same experiment in the 
month of July, with the same conditions and in the same 
time; the sparrows lost 21° of heat.* 

44G. We gradually pass from the intensity of summer’s 
heat through the autumn to the severity of winter’s cold, and 
back again through the spring; and as each of these oppo¬ 
site seasons comes upon us, we receive the constitution 
adapted to it, and endure the extremes of temperature with¬ 
out suffering. But we cannot leap from the one to the 
other with impunity. A resident of Massachusetts would be 
enervated by suddenly arriving in the West Indies in the 
winter; and if, after residing under the equator for a season, 
he should as suddenly return to Boston in January, he would 
suffer from the cold. 

447. The dwellers in warm houses, and the workmen in 
warm shops, retain the summer constitution through the 
winter more than the out-of-door laborers, and cannot bear 

* Influence of Physical Agents on Life, Part III. Chap. III. 



THE SKIN. 


191 


cold as well as they do without suffering, and therefore need 
more clothing when exposed to the same temperature. A 
shoemaker or student, going from his warm shop or room 
and taking the outside seat of the stage-coach, by the side of 
the driver, in winter, must wear thicker garments than his 
companion who is daily exposed to the weather; if he does 
not do so, he will suffer more than the coachman. Those 
who live in houses heated by furnaces, in which all the 
entries and rooms are more or less warmed, and who seldom 
go abroad, hardly receive the winter constitution in the 
proper season, and cannot bear exposure to the open air 
without much additional clothing. 


PART V. 
THE SKIN. 


CHAPTER I. 

The internal Structure needs Protection_Skin. — Cuticle: thick 

ened by Friction if gradually applied_Blisters_Corns. 

448. The inner framework and vital machinery of ani¬ 
mals— their lungs, heart, and blood-vessels—their muscles, 
nerves, and digestive apparatus — are all very delicate, and 
would ill bear exposure to the action of the elements, or even 
the contact with other bodies. They are, therefore, protected 
with some outward covering, which is different in different 
animals. Yet, in all, it stands between these organs of life 
and the external world. In man, and in many other animals, 
this outward covering is the skin, which is a soft and pliable, 
and yet a strong membrane, that is not easily injured or torn, 
does not suffer from contact with other substances, and will 
bear wide variations cf heat and cold. 




192 


PRACTICAL PHYSIOLOGY. 


449. The outer shin (Fig. XXVI. a , a) or cuticle , covers the 
body. It is lifeless and insensible. The hangnails of the 
fingers, the peeling of the lips when we have a cold, are parts 
of this skin. If we pinch them, we do not feel it. So, also, we 
may run a pin through this skin at the corners of the fingers 
or thumb, or trim the thickened skin of the heel, and suffer 
no pain. It does not ache with the cold nor suffer with the 
heat. It has no nerves to feel nor blood-vessels to give it life. 

450. The cuticle, sometimes called the scarf-skin , is 
formed by, and grows from, the true skin beneath it, and is * 
constantly casting off its surface in the form of powdery scales. 
But it is as constantly renewed. This process of change 
never ceases in health. Sometimes this outer layer peels ofl 
from the lips in case of a cold, or from the roots of the nails; 
but soon another takes its place. When it is peeled off, 
it leaves the true and sensitive skin bare and tender. Bat, 
when it is cast off naturally in dead scales, it leaves a layer 
behind, which protects the more delicate parts beneath. 

451. Over the whole of the child, and on the parts of the 
Fig. XXVII. Skin and perspiratory Apparatus highly magnified. 



a, a , Cuticle. 

b, b, True skin. 


c, c, c y Perspiratory glands. 
dy dy d, Perspiratory tubes. 



THE SKIN. 


193 


adult which are not exposed to contact witli other bodies, 
and especially on the lips, this cuticle is thin and delicate. 
But, whenever it is exposed to the elements or friction, it 
becomes thicker and tougher; for any friction, if moderately 
applied, instead of wearing it out, causes it to grow more 
and more; the under skin throws out more of the matter 
that forms the cuticle, and this latter is thickened and 
strengthened. This is most observable in the sole of the 
foot and palm of the hand; the more they are used, the 
thicker and harder their cuticle becomes, so that the bare¬ 
foot boy treads on the rough pavement without injury. 

452. Though the cuticle becomes thick and hard from 
friction and labor, yet these must be applied cautiously and 
gradually, otherwise the reverse will happen. When the stu¬ 
dent or clerk undertakes to cut wood, or rake hay, or row a 
boat, for several successive hours, the cuticle of his palms, 
instead of growing thick and hard, becomes thin and sore. 
The outer skin may be worn off, or it may separate from the 
other, and the under skin, instead of throwing out more mat¬ 
ter to be formed into cuticle, throws out a watery matter, 
which fills a little sack between them, and forms a blister. 

453. But if this friction had been applied gradually, and 
continued for a long time, it would have stimulated the inner 
skin to form more and more of the outer or scarf-skin, to 
meet the want and the pressure, instead of throwing out 
water, and causing pain and soreness. 

454. By the gradual application of friction, the skin be¬ 
comes so fortified with this thickened outer layer, that it will 
bear very rough usage without suffering; so that the hands 
of the stone-layer and of the mason are neither scratched nor 
inflamed by the rough stones, nor irritated by the lime in the 
mortar. In the same way, the hands of the blacksmith and 
the founder become accustomed and prepared to handle very 
hot and rough metals without being burned or suffering pain. 

455. But if one unused to labor with his hands attempts at 
once to become a stone-layer or brick-mason, he would soon 
find the tender skin of his hands blistered and torn, The 

17 


194 


PRACTICAL PHYSIOLOGY. 


new apprentice in a blacksmith shop or a foundery burns his 
hands in doing the very work which the older workmen do 
without any suffering. 

456. When the feet are pinched by new and very tight 
shoes, painful pressure is made upon the skin, and sometimes 
blisters are raised in walking. But, if this pressure be more 
gently and gradually made, and long continued, the cuticle 
becomes thickened on the prominent joints of some of the 
toes, by the formation of new underlayers. These layers are 
broad at the top and narrow at the bottom, and the whole 
thickening is somewhat wedge-shaped or conical, with its 
point inward. This is a com; and the shoe, bearing upon it, 
presses upon the tender flesh beneath, often producing acute 
distress. 


CHAPTER II. 

Cuticle defends true Skin from external Injury. — Nails, Hoof, and 
Horn. — Seat of Color. — True Skin has many Blood-Vessels and 
Nerves. 

457. The cuticle, placed between external objects and the 
true skin, protects it from their contact. It bears their hard 
usage, but suffers no pain. By means of this protection, we 
are enabled to handle, not only rough and hard substances, 
but many matters which would be poisonous to the more deli¬ 
cate skin beneath. The dyer or the chemist holds his hands, 
if the outer skin is unbroken, in strong mixtures, without 
pain or irritation; but if the cuticle is broken and the inner 
skin bare, great pain and sometimes disease are the conse¬ 
quence. Physicians often examine the bodies of those who 
have died of putrid diseases, and, if the scarf-skin of the 
operator is entire, no bad consequence follows; but, if there 
be the least cut or scratch of this cuticle, through which the 
poison can gain access to the under skin, very severe disorder, 
and sometimes death, ensue. Some, who thought themselves 



THE SKIN. 


195 


safe because they had no perceptible wound, and therefore 
exposed themselves to very virulent poison, have been infect¬ 
ed by the poison’s insinuating itself through the very slight 
rupture of the cuticle on the end of a finger, where a mere 
hangnail had been raised. 

458. Other parts, that grow out of this cuticle, have the 
same structure, and are endowed with the same properties. 
The nails of our fingers are productions from this membrane, 
condensed and made firm. Yet they have the same power to 
protect, and the same insensibility. The hoofs of horses, the 
horns of cattle, are similar; they have the same protective and 
the same negative character. 

459. The nail grows from the cuticle. It has its root 
(Fig. XXVII. c) in the inner layers of this membrane, and 
its under surface is closely attached to the true skin. It 
grows from the root forward. 

Fig. XXVII. Vertical Section of the Thumb and Nail. 

a, NaiL 
by Cuticle, 
c, Root of the nail. 
dy True skin. 

fy Fatty matter under the skin 
g. Bone. 

460. The hair (Fig. XXVIII. 6, c, &,) is composed of a sub¬ 
stance similar to that of the cuticle. It takes its origin in a 
pulpy bulb, (Fig. XXVIII. d,) which is situated below the 
true skin, (Fig. XXVIII. /.) It is fed by an artery, (Fig. 
XXVIII. a,) which supplies it with the material of growth. 
Within the skin, it is a tube containing a pulpy matter, (Fig. 
XXVIII. c.) In ill health, or in the later periods of life, this 
nutriment diminishes and the coloring matter ceases, and 
then the hair is white. Still later, the nutriment entirely 
fails, and then the hair falls out, and the aperture in the skin 
closes. 

461. The cuticle is continually casting off its outward layer 
in the form of little scales, so minute as to seem like dust; 




196 


PRACTICAL PHYSIOLOGY. 


Fig. XXVIII. Hair highly magnified. 


a, Artery. 

b, b, Tubular part, 

c, Pulpy part. 

d , Pulpy bulb. 

e , e, Cuticle. 

/, True Skin. 


in the form of little scales, so minute as to seem like dust; 
the form of the scales is scarcely visible, except on the head. 
This scurfy dust is constantly gathering upon the surface, 
and needs to be frequently washed off with soap and water. 
And when, after a long neglect of this duty, we rub the skin 
vigorously in a warm bath, we feel this matter gather in little 
rolls under the hand. After some fevers, this skin comes off 
in little flakes, like scales of bran, but not in health, except on 
the head. The loss of these outer layers is continually sup¬ 
plied by the new growth of layers underneath from the inner 
skin. This process of change gives the scarf-skin a constant 
freshness of substance. 

462. The cuticle is composed of several layers of thin 
scales. The outer and the oldest are transparent. Thepzg-- 
meiit zells, which are the seat of color, are situated in the 
innermost and the last-formed layer of the cuticle. The con¬ 
tents of these cells give the different shades to the various 
races of mankind, and to various individuals. This matter is 
white or flesh-colored in the European and North American, 
black in the African, yellow in the Mongolian, and copper- 
colored in the American Indian. It is this which is dark¬ 
ened or tanned by exposure to the sun‘ and bleached by pro- 





THE SKIN. 


197 


tection. Carpenter says, “ What has been termed the rete 
mucosum is simply the last-formed portion of the cuticle.” 

463. The various coloring of this inner layer of the cuti¬ 
cle gives to some animals their varied hues — to the serpent, 
the frog, and the lizard, and some fishes, which have a splen¬ 
dor of hue almost equal to polished metal. Goldfish and the 
dolphin owe their difference of color, and the brilliancy of 
their hues, to the color of this layer of skin. 

464. Underneath the cuticle is the true shin , (Fig. XXVI. 
ft, ft,) the seat of all the active functions of the cutaneous mem¬ 
brane. This layer is a dense and thick membrane, and com¬ 
posed of firm and strong fibres, that are interwoven like the felt 
of a hat. It is almost filled with minute blood-vessels, so many 
that a large proportion of the blood of the whole system flows 
in them. If we cut the outer skin, no blood flows, be¬ 
cause no blood is there; but if we cut through that and 
into the inner skin, we cannot fail to wound some of these 
vessels. 

465. In health, when every thing goes on well in the ani¬ 
mal body, the blood is properly distributed in all the organs, 
and each receives its due proportion; then it flows freely 
through the vessels of the skin, and the surface is florid and 
the cheek is rosy. But cold contracts the cutaneous vessels, 
and lessens their capacity for blood. The cutaneous circu¬ 
lation is sometimes influenced even by the state of the mind 
and the affections: the blood flows more abundantly in the 
capillaries of the face when the modest youth blushes, or 
when one is excited; and it is easily driven away, and the 
cheek turns pale, when one is oppressed with fear, or is over¬ 
come with anxiety. 

466. This skin is furnished with a great quantity of 
nerves, for it is endowed with an exquisite degree of sensi¬ 
bility to pleasure and to pain; and it is also the seat of the 
sense of touch. In man, the nerves are more abundantly dis¬ 
tributed to the skin than to the other organs. But those 
animals which are covered with hair, feathers, or scales, have 


198 


PRACTICAL PHYSIOLOGY. 


not this large supply of cutaneous nerves, nor this acute sen¬ 
sibility of the skin. 

467. Underneath this skin there is a layer of fat, which 
varies in thickness in different parts of the body. It is very 
thick in the palm of the hand and the sole of the foot, and 
affords a cushion to meet the pressure that comes upon those 
or other parts that need this support; while in the forehead 
and on. the back of the hand it is very thin, for there it is not 
needed. 


CHAPTER III. 

Functions of the Skin: Exhalations : Perspiration. — Sensible and 
insensible Perspiration. — Quantity. — Experiment at Phoenix Gas 
Works. 

468. The skin is the outlet for a good proportion of the 
waste of the body. Some goes off in the form of carbonic 
acid, some in the oil, but the greater part in form of perspi¬ 
ration. Sanctorius, a celebrated medical writer, carefully 
weighed himself and all his food, and drink, and excretions, 
daily, for thirty years; and, after all this observation, he con¬ 
cluded that, of every eight pounds which were taken into his 
system each day, five passed out through the skin. 

469. Seguin, a philosopher, weighed, and then enclosed 
himself in a bag, which was glazed so as to prevent the per¬ 
spiration from passing through it. He found that the largest 
quantity of perspiration that passed off in a day was four and 
a half pounds, and the smallest quantity was twenty-four and 
three quarter ounces; the medium was thirty-three ounces. 

470. This is the insensible perspiration; for, although it 
amounts to about two pints a day, it is not usually percepti¬ 
ble; it passes off in such minute portions, and is so com¬ 
pletely dissolved in the air, that we do not perceive it. Yet 
it can be perceived by holding the hand, apparently dry, near 



THE SKIN. 


199 


a cold mirror, which will condense the invisible vapor and 
soon be covered with a slight dew; or if we put the hand 
into a large tumbler or glass pitcher previously wiped dry, 
and wind a towel about the wrist, so that nothing can pass 
out at the mouth of the glass, we shall then soon see the 
moisture gather upon the inner surface. This can be noth¬ 
ing more than the condensed exhalation from the hand. 

471. This is called the insensible perspiration, in distinc¬ 
tion from the sensible or visible perspiration, which flows in 
drops from the skin when we are excited or are unusually 
warm. The insensible perspiration never ceases to flow dur¬ 
ing health; and under all circumstances, if the skin is in a 
good condition, it is not interrupted. But the sensible per¬ 
spiration flows only occasionally, and, though more abundant 
sometimes than the other, yet the whole amount is much less. 
In the cold-blooded animals, — the toad, serpent, &c., — the 
insensible is six times as great as the sensible perspiration. 
The.difference in man is not so great as this, yet it is con¬ 
siderable. 

472. The sensible perspiration — the sweat — is at times 
very great, and occasionally we saturate our clothing with it 
in a very short period. Some experiments were performed, 
and observations made, at the Phoenix GasWorks, in London, 
Nov. 18, 1836, to determine how large a quantity would be 
thus thrown out from the body under favoring circumstances. 

473. “ Eight of the workmen regularly employed at this 
establishment in drawing and charging retorts and in making 
up the fires, which labor they perform twice a day, commonly 
for the space of one hour, were accurately weighed in their 
clothes immediately before they began and after they had 
finished their work. On this occasion, they continued at 
their work exactly three quarters of an hour. In the inter¬ 
val between the first and second weighing, the men were 
allowed to partake of no solid or liquid, nor to part with either. 
The day was bright and clear, with much wind. The men 


200 


PRACTICAL PHYSIOLOGY. 


worked in the open air, the temperature of which was 60° 
Fahrenheit. The barometer was 29° 2 5' to 29° 4'.” 

474. These eight men lost, during these three fourths ot 
an hour, by perspiration from the skin, various quantities. 


The first lost 2 lbs. 8 oz. 
second, 2 “ 9 “ 
third, 2 “ 10 “ 


The fifth lost 3 lbs. 12 oz. 
sixth, 3 “ 14 “ 
seventh, 4 “ 2 “ 

fourth, 3 “ 6 “ eighth, 4 “ 3 “ 

The average loss of all was 3 lbs. 6 oz.* 

475. This constant perspiration, and the exhalations from 
the lungs, maintain the permanency of the weight of man; 
so that, although he eats and drinks from four to six pounds 
a day, his body at night weighs no more than on the day 
before; and, if one man eats and drinks more than another, 
he has more pulmonary and cutaneous excretions, and the 
superabundance is thus carried away. 

476. This whole amount of cutaneous exhalations, sensi¬ 
ble and insensible, will average about the same in a healthy 
individual, from day to day or from month to month. 
Yet there are many circumstances that cause it to vary. 
Climate and season influence it; it is more in summer than 
in winter; philosophers estimate it to be forty ounces in the 
south, and twenty ounces a day in the north of Europe. 
Active exercise — running, hard labor—will increase it, 
and make the sweat visible, so as to run abundantly in drops. 
Unusual quantities of clothing prevent the radiation of heat, 
and cause it to accumulate; the skin then becomes warmer, 
until an increase of perspiration occurs and relieves by its 
evaporation. 


* Smith’s Philosophy of Health, Vol. II. pp. 391,392 



THE SKIN. 


201 


CHAPTER IV. 

Perspiration differs in various Temperatures. — More in dry than in 
moist Air_Prepared in Glands for the Purpose. — Some Ani¬ 

mals do not perspire.— Oily Excretions from the Skin. — Tight 
Clothing, Hats, &c., prevent Removal of these Excretions. 

477. This perspiration differs in various conditions of 
the atmosphere. Heat increases the activity of the cutane¬ 
ous blood-vessels, and the perspiratory action, and also the 
capacity of the air to receive vapor. (§ 349, p. 152.) Evapo¬ 
ration is therefore more rapid in warm than in cold weather. 
A moving atmosphere brings to the body a constant suc¬ 
cession of layers of dry ?iir, which absorb the moisture more 
rapidly. The perspiration is therefore more free in a windy 
than in a still day; and, if the wind is very dry and hot, 
this evaporation is still further increased. The sirocco, 
which comes over Sicily from the south, is so dry and hot as 
to produce in the skin a parching and painful dryness, and 
sometimes excites disease. 

478. When the air is saturated or loaded with moisture, 
the evaporation is checked, and the perspiration is not car¬ 
ried off so freely; and sometimes this interruption causes 
a serious disturbance and burden to the system. The waste 
that is carried off through the skin gives important relief to 
the whole body, and, if this is interrupted, oppression follows, 
and the frame is languid. In some of the sultry dog-days, 
we are languid, because the atmosphere, being already filled 
with vapor, does not carry off the watery exhalations of the 
skin, and relieve the body. From this cause, internal dis¬ 
eases prevail more in low and damp situations of warm 
climates than in dry. On the banks of the southern and 
western rivers, this is most painfully manifested. 

479. In this work of perspiration, the inner skin performs 
all the active duty. It not only throws this fluid out, but it 
originally forms it out of the elements which are found in 
the blood. This work of formation is done in little glands 


202 


PRACTICAL PHYSIOLOGY. 


which are placed (Fig. XXVI. c,c,c,) just beneath the skin; 
and the perspired fluid is carried from each one of them to 
the surface, through a minute tube which is attached to the 
gland, and leads outward (Fig. XXVI. d,d,d)) There are three 
thousand five hundred and twenty-eight of these little tubes 
on each square inch in the palm of the hand, and twenty- 
eight hundred on each square inch throughout the whole 
body, making seven millions of perspiratory tubes on a man 
of average size. 

480. The power of relieving the body of its superfluous 
matter or moisture by perspiration is not common to all ani¬ 
mals. Men and horses sweat, and thus find an outlet for 
these matters, and for the excess of heat. But dogs have 
no such means of relief; when they are heated by exercise, 
they loll their tongues, and the evaporation from their sur¬ 
face aids in the cooling process. Cattle, when heated in 
the summer, effect the same purpose in the same manner. 

481. There are other secretions of the skin beside the 
watery perspiration. The skin is soft and oily, it is supple, 
and in health it is never dry and hard. To produce this 
condition, there are numerous little glands placed within 
the skin, whose business it is to gather out of the blood the 
elements of an oily matter, and with them compound this 
substance, and then throw it out upon the surface. If the 
preparation of this oil is checked, the skin is dry and hard; 
but, when this work is well performed, the skin is soft and 
supple, and pleasant to the touch. “ It is this fluid which 
soils the linen, and which causes the water to collect in 
drops, when we come out of the bath.” These oil-glands are 
more abundant in the face and in other parts exposed to the 
air, and in the arm-pits, &c., where one part of the skin comes 
in contact with another. But through all the skin there are 
enough to keep the surface soft, and in a natural condition. 

482. This oily secretion is sometimes odorous, and in 
some parts unpleasant to the smell, and even in some men 
fetid. It is more so under the arms than elsewhere; but in 
some persons the whole surface throws out an offensive mat- 


THE SKIN. 


203 


ter. This odor is not the same in all persons; it is said that 
each one has his own peculiar smell, by which the dog can 
scent his master at a great distance. 

483. These excretions are intended to he carried , not 
only out of, hut away from, the body. If suffered to remain, 
they are mixed with the dust in the air, and the particles of 
the scarf-skin that scale off; and they, together, form a thick, 
crusty matter, which fills the pores and interrupts the trans¬ 
mission of the natural fluids. Then the skin becomes com¬ 
paratively stiff and hard, and Joses its suppleness and agreeable 
feeling, and is also more liable to suffer from the effects of 
cold. The perspiration is usually carried away by mere 
evaporation. If, therefore, it have sufficient access of air, 
it will generally be removed. 

484. The air is an important agent in the action of the 
skin. It gives it oxygen, and takes from it some carbonic 
acid. It removes the perspiration and some of its superflu¬ 
ous oil. It is necessary, then, that the air should reach the 
body. For this purpose, the clothing should be loose and 
porous. Tight clothing, water-proof dresses, oil-cloth, India 
rubber garmentSj glazed coats, and even leather clothing, 
prevent the access of air, and the transpiration of the per¬ 
spired fluids; and, inasmuch as they thus interfere with the 
functions of the skin, they are unhealthful, and improper to 
be worn. India rubber shoes retain the perspiration, and 
the feet that wear them are often wet. It is a common com¬ 
plaint that glazed caps worn in summer, however light they 
may be, make the head ache. This is caused by the close¬ 
ness of their texture, which prevents the free passage of the 
vapor. The cap fits so closely to the head, that no vapor 
can escape, and its impervious texture offers no avenue 
through which the perspiration can pass away. 

485. For the same reason, hats made of felt are too close 
for health and comfort. Ventilated hats are made on true 
physiological principles, because they allow the cutaneous 
excretion free passage outward. If a tight felt hat is worn, 
it is better to be sufficiently large to afford room for much 


204 


PRACTICAL PHYSIOLOGY. 


of this vapor to escape. And even then we find great relief 
from frequently taking off the hat to air the head, or rather 
to air the hat itself, by letting the enclosed air, which is 
saturated with vapor, pass away, and fresh air take its place. 


CHAPTER V. 

Connection between the Skin and the internal Organs. — Stomach, 
Lungs, Muscles, &c. — Effects of Cold on different People va¬ 
rious. 

486. There is a very intimate connection between the 
shin and the internal organs of the body. The blood flows 
from one common centre through various channels to the 
minute vessels of the skin, and all the parts included within 
it. If the outer vessels are closed, and the circulation is in¬ 
terrupted there, the blood must flow in greater abundance 
into the inner vessels. On the contrary, if the inward flow 
is impeded, it must find passage outwardly. In either case, 
the balance of the circulation is disturbed, and the over¬ 
burdened part is disordered. If we expose ourselves to 
sudden or long-continued cold, the surface becomes chilled, 
the cutaneous vessels contracted, the perspiration checked, 
and then some of the internal organs bear the burden which 
usually belongs to the skin. The check of the perspiration 
is not the cause of the disturbance; it is merely one of the 
consequences of the previous interruption without, and a 
sign of other troubles within. 

487. We have seen the influence of tea, taken into the 
stomach, upon the cutaneous circulation and functions. 
(§441, p. 188.) Certain medicines, taken into the stomach, 
have the same effect. A man under the operation of an 
emetic often sweats profusely. Some kinds of food, — such 
as shell-fish, — when eaten, will cause the skin to break out 
with the nettle rash. In some cases of indigestion, the same 
effect is produced. In September, 1845, I saw a child 



THE SKIN. 


205 


which had suddenly broken out with this rash, from eating 
indigestible food. Its skin from head to foot was covered 
with this scarlet eruption. But, as soon as the stomach was 
relieved of its disturbing cause, the rash departed, and the 
skin resumed its natural color. 

488. The lungs and the shin are intimately connected 
by their mutual sympathies. They cooperate together in 
carrying off much of the waste of the body. They bear 
each other’s burdens. When the circulation is checked in 
the skin, it may be throivn more upon the lungs; and an in¬ 
crease of the flow of blood in the skin relieves the lungs 
when they are oppressed. Every one is familiar with the 
character and operation of a cold, and with the common 
remedy of a sweating process. A man puts on a thinner 
dress, or goes into a colder atmosphere than he has been 
accustomed to. The cold of the air diminishes the ca¬ 
pacity of the blood-vessels of the skin, interrupts the cu¬ 
taneous circulation, and checks the perspiration. The 
balance of the circulation is disturbed, and the lungs are 
compelled to receive more blood than usually belongs to 
them. These organs are then oppressed, and the breathing 
becomes somewhat difficult; or the blood-vessels in the 
mucous or lining membrane of the air-cells nnd air-tubes of 
the lungs may become enlarged, and carry more blood, and 
throw out more mucus, which is coughed up. The sufferer 
then takes hot teas, or other stimulating remedies that excite 
the cutaneous arteries, and he covers himself under an un¬ 
usual quantity of bed-clothing. The skin then is heated; its 
arteries are enlarged and more active, and carry more blood; 
the balance of circulation is restored, and the perspiration 
breaks out profusely; and then the lungs are relieved. 

489. A similar connection exists between the shin and 
digestive organs . In summer, and in warm climates, an in¬ 
terruption of the cutaneous circulation more frequently dis¬ 
turbs the organs of nutrition, and excites them to excessive 
action, and produces a painful disturbance; and, on the con¬ 
trary, the restoration of the external circulation and action 

18 


206 


PRACTICAL PHYSIOLOGY. 


is one of the means of relieving the internal disorder. Ex¬ 
posure to cold is sometimes followed by disturbance in the 
organs of locomotion, and then we have rheumatism, pain, 
and sometimes swelling in the muscles and joints. In this, 
as well as in the other cases, the disorder is removed when 
the balance of circulation is reestablished; for, when the 
natural perspiration and the other cutaneous functions are 
restored, the rheumatism diminishes, and the limbs and 
muscles become easy. 

490. We thus see that the skin stands not alone; but is 
intimately connected with the internal apparatus of life, and 
does not suffer, without their sympathy, nor enjoy the full 
measure of health, without their participation in a greater 
or less degree. 

491. Persons differ in the degree and distribution of their 
health and strength; all their organs and systems may not 
have the same power of action, or of resistance to disturbing 
causes. In one man the lungs, in another the organs of 
locomotion, and in a third the digestive apparatus, and in a 
fourth the nervous system, may be weaker than the other 
organs. It is the weaker internal organ that is in the most 
danger of suffering, when the balance of circulation is dis¬ 
turbed. Several men may be exposed to a storm together, 
and all may be drenched with rain and chilled. In all, the 
cutaneous circulation is disturbed, and the perspiration 
checked, the blood is thrown inward, and some internal 
derangement may follow. But this differs according to the 
previous state of the constitution. One of these men takes a 
cold in his lungs, the second is attacked with a pleurisy, the 
third with a disorder of the digestive organs, the fourth with 
rheumatism, the fifth has a fever, the sixth a headache, while 
the seventh has sufficient vigor of constitution to resist the 
internal disturbance, and to produce immediate reaction in 
the vessels of the skin, and restoration of all its healthy 
functions. 

492. There are many conditions of the body that affect 
the insensible as well as the sensible perspiration. All 


THE SKIN. 


207 


diseases that prevent the circulation in the skin interrupt 
the flow of this fluid. In some of the stages of fever, the 
skin is dry and parched. But, without disease, the perspira¬ 
tory action is never stayed, so that, whenever we find the 
skin dry, we may be assured that all is not right in the 


CHAPTER VI. 


Skm is an Absorbent. Food and Drink sometimes taken into the 
Body through the Skin. — Medicines. — Contagion. — Poisons 
absorbed by the Skin. — Absorption more active in the Night than 
in the Day. 

493. The skin has other duties to perform , besides that 
of carrying off the waste of the body; it is an absorbent as 
well as an exhalent. In certain conditions, it takes some 
matters into the body, while it throws others out. But this 
is not usually done in a period of health; it is rather when 
in a state of disease. Nevertheless, absorption is not always 
indicative of disorder. It may be used to prevent or relieve 
derangement of the system. It is the most active when the 
fluids of the system are reduced in quantity, and when 
nutrition is not well sustained. 

494. Sailors, when destitute of fresh water, wear their 
clothes wet with sea-water. Then the skin absorbs and car¬ 
ries some of this fluid into the body; and thus their thirst is 
allayed, and sometimes entirely relieved. Dr. Currie relates 
a case of a patient, who, from disease of the throat, was 
unable to swallow any thing, and was therefore in danger 
of immediate death from starvation. His flesh was rapidly 
wasting away; he suffered extremely from thirst, and was 
nearly exhausted. While in this state of suffering, he was 
placed, night and morning, in a bath of milk and water. 
After this was begun, his body ceased to waste; and, while 



203 


PRACTICAL PHYSIOLOGY. 


this course was pursued, he maintained his weight, and the 
thirst ceased to be troublesome. In thi3 case, the skin 
absorbed sufficient fluid and nourishment to maintain life. 

495. One of the men who were subjected to the sweat¬ 
ing experiment of Dr. Smith (§§ 473, 474, p. 199) — the one 
who lost two pounds and fifteen ounces — went into a hot 
bath at 95°, where he had remained exactly half an hour. He 
< r as reweighed on coming out of the bath ; and then it was 
found that he had gained half a pound. This must have 
been by the absorption of water. In the case of Ann Moore, 
(§ 97, p. 59,) there was some matter constantly passing off 
through the lungs, and doubtless some perspiration. Yet, 
for years, she took nothing through the mouth but a little 
tea, and not enough of this to sustain life and to meet the 
wants of respiration, and yet she did not waste away. The 
body must have been sustained by matter which was absorbed 
from the atmosphere through the skin. 

496. Other substances beside fluids may be thus ab¬ 
sorbed. The odor of camphor or of garlic may be perceived 
in the breath, when a plaster of one of these substances is 
worn upon the skin. Medicines are sometimes thus intro¬ 
duced into the system; some liniments may be rubbed into 
the skin, and entirely absorbed. Antimony rubbed over the 
stomach is said to produce vomiting. Mercury, in the same 
way, may bring on salivation. Men at work in lead mines, 
or in an atmosphere of lead or lead paints, are often troubled 
with what is called the lead colic , from the absorption of 
particles of lead through the skin. 

497. But what should set at rest all doubt of the absorb¬ 
ing power of the skin is the effect of contagion. The 
slightest quantity of matter from the pustule of the kine pox, 
when applied to the inner skin under the cuticle, excites 
disease in the whole system. So other contagious diseases — 
such as small-pox—are conveyed by the bare touch. Even 
the matter of the latter disease which may be rubbed from 
the skin, and lodged on the clothing or the bed, will be ab 


THE SKIN. 


209 


Borb^d, and convey the disease to any one who should next 
sleep in that bed or wear that garment which had been thus 
infected. The poison of dogwood or ivy is absorbed by the 
skin of the susceptible, if they but touch the plant; and the 
disease, being excited within the skin, extends beyond the 
point of contact, and sometimes over the whole surface. 

498. The poison of bad air is supposed to be thus ab¬ 
sorbed. In marshy countries, where the exhalations from 
the earth infect the atmosphere with the seeds of fever 
or other disease, the people whose lungs breathe, and whose 
surface is in contact with this air, receive the poison by 
the absorbing power of their skin and their air-cell's 

499. This absorbing power is more active at night: then 
contagion of disease and infection of bad air act with more 
readiness and vigor, and men are more liable to be attacked 
by prevailing epidemics through the air, or by contagious 
diseases from contact with those already diseased, than in the 
daytime. It is more active when the body is badly nour¬ 
ished than when it is well fed. Hunger and thirst increase 
the absorbing power of the skin, and good nutriment 
diminishes it. So that one is more susceptible of disease 
before than after breakfast, (§113, p. 56;) and cautious 
physicians fortify themselves with nourishment in the morn¬ 
ing, before they visit patients who are suffering from epi¬ 
demic or contagious diseases. 

500. Any poisonous or offensive matter in contact with 
the surface stimulates the cutaneous absorbents. The nat¬ 
ural excretions of the skin, — the perspiration, the oil, and the 
dead cuticle, — being the offensive waste of the body, if not 
removed from it, excite this tendency to absorption; and 
when they are not washed away, or are confined too much by 
impervious clothing, they themselves are often taken back, ta 
irritate and disturb the system. 

18 * 


210 


PRACTICAL PHYSIOLOGY. 


CHAPTER VII. 

Skin Seat of Touch. — Sensibility of Skin differs in different Parts, 
and in different Persons. — If the outer Skin is thick or foul, the 
Sensations of the inner Skin are dull. — Sense of Touch can be 
cultivated. — Blind have acute Sense of Touch. 

501. The sense of touch is situated in the skin. It is 
not in the cuticle, which is insensible, but it is in the true 
or inner skin, which is very sensitive and exceedingly alive 
to pain, and suffers from contact with any matter, however 
soft and bland. Strip off the outer skin and expose the layer 
beneath, and this, which before was comfortable when pro¬ 
tected, will now, in its nakedness, ache with pain. Even the 
air is disagreeable to it. But this sensibility to pain is un¬ 
equally distributed. The sensibility to contact, or the acute¬ 
ness of the sense of touch, also differs in the various parts of 
the skin. Some parts are more plentifully supplied with 
nerves than others. The ends of the fingers, the lips, and 
the face of man, and the end of the elephant’s trunk, have 
more nerves and more sensibility than the back or the chest; 
these and all other uncovered parts have more than the head, 
which is covered over with hair. 

502. The cutaneous sensibility is as unequally distrib¬ 
uted as are the nerves. It is the greatest at the tip of the 
fingers, and the least in the scalp. The sensibility of touch 
is more acute in the right than the left, but the sensibility 
in regard to heat is greater in the left than in the right hand; 
for, “ if the two hands were immersed in warm water of the 
same temperature, that in which the left was plunged would 
feel the warmest.” The sensibility differs very much in dif¬ 
ferent individuals, so much “ that that which amounts to 
absolute torture in one is a matter of almost indifference to 
the other.” The sensibilities are more acute in the young 
than in the adult, and in the latter than in persons of ad¬ 
vanced life. They are greater in the female than in the 
male; in the sanguine and nervous than in the phlegmatic 


THE SKIN. 


211 


and bilious temperaments, and in those enfeebled by disease 
than in the sound and robust.” * 

503. The facility , with which cutaneous sensations are 
received , depends upon the condition of the outer skin. 
When it is thick, as on the palm of the hand or the sole of 
the foot, sensation is somewhat interrupted. The seamstress 
finds it more difficult to feel and distinguish minute differ¬ 
ences of objects with the fingers with which she uses the 
needle than with the others. The difficulty is, not that the 
sensibilities in these fingers, as in the palm or the sole, are 
more blunted than in the others, but that a thicker shield 
of cuticle stands between the nerves in the inner skin, and 
the object which is to be examined. 

504. The sense of touch differs very widely, not only in 
various parts, but in various persons. Beside the natural 
and original differences of sensibility from organization, 
there is a very great difference owing to education; for 
this sense can be educated to a very high degree, so that one 
person may be able to perceive objects and characters which 
another, whose sense of touch is less cultivated, could not 
recognize. 

505. It is a remarkable provision of a benevolent Provi¬ 
dence that, when one sense is lost or impaired, the others 
become more acute, so as to compensate in a good degree for 
the defect. Thus the blind have or acquire a niceness of 
touch which the seeing never possess. Their method of 
reading is a singular proof of the extent to which the culti¬ 
vation of the sense of touch may be carried. Their books, 
instead of being printed on soft paper, and with colored let¬ 
ters, are printed on stiff paper, and with raised letters. Their 
pages are perfectly white, but the surface is not smooth. Their 
letters stand out as if carved in wood. The blind move their 
fingers over these, and, by the sense of touch, they recognize 
the shape and kind of each letter almost as readily as others, 
who see, recognize letters that are printed with ink. It 


* Wilson on the Skin. 


212 


PRACTICAL PHYSIOLOGY. 


is interesting to notice with what rapidity these sightless 
children can read. Th§y must of course perceive one letter 
at a time, and, at the end of each word, determine what the 
several letters spell. Yet, with this additional mental pro¬ 
cess, they read nearly as fast as w r e do with the use of our 
eyes. This seems very easy when we see them do it; but if 
we shut our eyes, and then apply the fingers, not to a whole 
word, but to a single letter, — the letter a, for instance, — we 
shall find it is not so easy for the untrained to decipher the 
raised marks. If we further attempt to read a word or sen¬ 
tence, we shall be lost in the mazes of indistinguishable 
characters. 

506. The blind are compelled thus to cultivate the sense 
of touch, to compensate for their deficiency of sight. But 
the power so to do is not confined to them. We all can do 
the same, if we apply the same diligence; and this we could 
do if we had as strong a motive as they have. The cloth- 
dresser learns to distinguish, by aid of the sense of touch in 
his fingers, the qualities ol material, or minute differences 
of texture, which others cannot detect. The miller, in the 
same way, detects the various qualities of meal and flour, 
which escape the notice of others. In a great many of the 
arts of life, the sense of touch is thus educated to be used 
for minute and useful purposes. 

507. This sensibility is blunted by several causes. Cold 
remarkably diminishes it. Our skin is numb when exposed 
to a very low temperature, so that men sometimes cut or 
bruise themselves, in winter, without feeling it; and the first 
intimation which they have of their injury is the sight of 
their flowing blood. This sensibility is also impaired by the 
natural excretions of the skin, by the mixture of the dead 
scarf-skin, oil, and perspiration, with the dust and dirt, if not 
removed from the surface. The blind man will wash his 
fingers before he attempts to read his raised letters; and 
the cook will pass through the same process when she leaves 
her ordinary work, and takes up her fine sewing. 


THE SKIN. 


213 


CHAPTER VIII. 

Animal Heat permanent. — Skin regulates it. — Excess of Heat 
carried off by Evaporation of the perspired Fluids. — Cold 
Sweats. — Sensations of Heat and Cold comparative. 

508. The skin is itself a had conductor of heat; that is, 
it does not allow heat to pass easily, either outwardly or 
inwardly, and therefore it is a good protector against high or 
low temperatures. The natural and usual temperature of 
the body is 98°; but the surrounding air is often at 100° in 
summer, and at 0 in winter; and, in some extreme climates, 
it is 30° warmer, or 150° colder, than our bodies. In the 
experiments of Sir Charles Blagden, (§ 402, p. 172,) it was 
more than 160° higher than the standard of 98°; and yet in 
neither case is the heat of the body materially changed. In 
the heated room, a thermometer placed in the mouth was 
hardly raised, and, beyond the arctic circles, it scarcely fell 
below our usual temperature. 

509. There is, of course, a constant tendency to radiation 
of heat from the skin when the air is colder than our bodies, 
as from any other substance: and, on the other hand, there 
must be a tendency to receive heat from the air when that 
is warmer than the body. In the first case, in cold weather, 
more internal heat is produced, (§ 443, p. 189,) to supply 
loss from increased radiation. In warm seasons, the evapo¬ 
ration of the perspiration absorbs the excess of animal heat, 
and thus the equilibrium of the internal temperature is 
maintained. 

510. The evaporation of the cutaneous fluids is the outlet 
of much of the surplus heat. (§ 441. d. 188.) Every one is 
familiar with the fact, that a wet skin is colder than a dry 
one, because the evaporation carries off more of the heat. 
The inhabitants of hot climates make use of this princi¬ 
ple, and put water into porous iars, the surface of which is 
constantly wet with the moisture that oozes through; and 


2J4 


PRACTICAL PHYSIOLOGY. 


the rapid evaporation of this cools the water within. Even 
ice may be thus produced. We are therefore cooler when 
we sweat. Blagden found great relief, in his oven, from the 
profuse perspiration which was rapidly evaporated. 

511. The cooling power of the air is influenced by other 
states besides its temperature. A dry atmosphere, by in¬ 
creasing evaporation, cools the body more rapidly than air 
saturated with vapor. Winds have the same effect. Even 
if the air is warmer than the body, if it is in motion and dry. 
it cools us; so that a lady’s fan, at summer’s noon, when the 
thermometer stands at 100°, two degrees warmer than the 
flesh, affords a pleasant coolness, by moving the air, and 
hastening the evaporation. So slight a motion of the air is 
thus perceptible by the increasing coolness, that men, when 
they cannot distinguish the direction of the wind by its force 
upon their bodies, or even by the movements of leaves of 
trees, often wet a finger, and, holding it up to the air, dis¬ 
cern, by their sensations, which is the colder side. This 
determines the course in which the air is moving. 

512. In order that the skin should passively permit the 
heat to pass off by radiation, or actively throw it off by 
perspiration, it must itself be in good health. It must be 
able to prepare within itself just as much fluid as will, by its 
evaporation, carry off the surplus heat, and no more; other¬ 
wise we may be too hot or too cold. 

513. In some states of disease, men suffer from a con¬ 
stantly dry and parched skin. Their flesh burns within, and 
the accumulating heat finds no outlet, for the skin affords no 
relief. In other disorders, they are prostrated with a pro¬ 
fuse and cold sweat. The skin pours out the perspiration 
like water, and this, by evaporating, creates a constant and 
painful demand for heat; and then the patient finds it im¬ 
possible to keep warm. 

514. Although it is through the sensibility of the skin 
that we perceive things to be hot or cold, yet this is by no 
means an exact measurement of the degree of heat; for 
the apparent and sensible temperature of any substance is 


THE SKIN. 


215 


merely relative to the previous sensations. If, after we have 
been handling snow, we take a piece of iron heated to 50°, 
it feels to us warm. But if another, who had been holding 
his hands in warm water, at 98°, should take up the same 
iron at 50°, it would seem to him cold. If one should come 
from the outer air of a cold day in winter, where the ther¬ 
mometer is at 0, and enter a cellar where the temperature is 
at 50° or 60°, he would feel a pleasant sensation of heat, and 
call the cellar warm. But if, at the same time, another 
should descend from his parlor, heated to 70°, into the same 
cellar, he would complain of cold. 

515. It is no uncommon circumstance for two travellers 
to meet midway on the side of a high mountain. One is 
coming from the top, where snow covers the ground and the 
air is wintry; the other is going up from the valley below, 
where summer reigns. The descending traveller, coming 
from the cold region, and finding the air warmer than that 
which he has just left, complains of the oppressive heat, and 
throws off his woollen clothes and puts on his summer gar¬ 
ments ; while the ascending traveller, coming from another 
atmosphere, much warmer than the present, complains of 
the cold, and changes his summer for his winter clothing. 
Both these men are exposed to the same temperature, but 
have very opposite sensations. 

516. Every thing which depresses the power and energies 
of life diminishes the production of internal heat , (§ 434, 
p. 186,) and also lessens the protective power of the skin 
against the external cold. Under the influence of hunger 
and fatigue, and the consequences of exhausting disease, 
and when overborne by the depressing passions and emo¬ 
tions— grief, despondency, anxiety, and fear, — the skin has 
less power to defend us from the extremes of heat and cold, 
and we are then more uncomfortably hot in high tempera¬ 
ture, and suffer more from the low. But the contrary hap¬ 
pens when we are well-fed and fresh, when we are vigorous 
and cheerful, and when we are animated with hope or ex¬ 
hilarated with confidence. 


216 


PRACTICAL PHYSIOLOGY. 


CHAPTER IX. 

Clothing needed to prevent excessive Radiation of Heat. — Parts 
usually clothed need more Protection than others. — Habit of 
Dressing affects the Necessity. — No positive Law for the Amount 
of Clothing. 

517. The skin is thus shown to perform three offices. It 
carries off much of the waste of the system, by means of 
perspiration, oil, and carbonic acid. It absorbs some mat¬ 
ters from the atmosphere and other contiguous substances. 
It regulates the transfer of heat from within outward, and 
prevents its coming inward from without. 

518. It is a natural question to ask, whether the skin can 
do this alone, or does it require our aid to enable it to per¬ 
form these functions faithfully and successfully? We are 
so much the creatures of habit, we have been so accustomed, 
through many years, and even from generation to generation, 
to cover the body with clothing, that it is not easy to tell 
how great a degree of cold could be borne upon the naked 
surface. As it is, there are not many days, even in summer, 
when we should feel as comfortable as we now do, if those 
parts of the body which have always been clothed were left 
unprotected. 

519. Certain it is that the heat is constantly prepared 
within the animal system; and it is equally evident that, 
when the body is warmed to its natural and usual degree of 
98°, the excess beyond that must pass off. As much is then 
to be thrown out as is added, and this is done mostly through 
the skin. But it is not so certain that the skin could, un¬ 
aided by clothing, regulate this transmission of heat so ex¬ 
actly that the internal temperature would not vary from its 
usual standard. Whatever the natural protective power of 
the outer surface might have done, if we and our fathers had 
from the beginning, lived in a state of nature, there can be 
no doubt that we and all civilized men, in temperate and 


THE SKIN - . 217 

colder climates, now need the aid of clothing to protect our¬ 
selves from cold, during most of the year. 

520. There is a very great difference in the present pro¬ 
tective power of different parts of the skin; and this varies, 
also, in different persons, according to their various habits. 
The air is seldom so cold as to compel us to cover the face, 
or even the upper part of the neck. These parts have 
always been exposed to the severities of winter, and they 
have borne them, and do now bear them, without suffering. 
But the chest and the back would hardly bear the open ex¬ 
posure to the weather of the warmest day of the summer, 
without suffering from chill. 

521. The female costume usually exposes the neck and 
the upper part of the chest, and even sometimes a portion of 
the back and shoulders. But women do not complain of 
suffering materially from this exposure. The dress of men 
covers the entire chest, shoulders, and back, and most of the 
neck; and they seem to be none too warm. But if a man 
accustomed to dress thus should expose his skin as women 
do, or even if he were to leave off his cravat, after wearing 
it, in winter, he would immediately feel uncomfortably cold; 
and, if this exposure were continued for any length of time, 
he would so change the balance and direction of the circula¬ 
tion that the blood would be thrown inwardly upon the lungs 
or throat, and he would take cold, and perhaps severe dis¬ 
ease would follow. 

522. The North American Indian wears much less 
clothing than his civilized neighbors. While we cover our¬ 
selves from neck to feet, and leave no part of the surface 
exposed, the Indian is satisfied and comfortable with his 
blanket for his back and shoulders, his girdle for his loins, 
and his moccasons for his feet. His limbs and his breast are 
bare. In the costume of the Highlander, who lives in the 
northernmost parts of Scotland, the kilt, or the short petti¬ 
coat, scarcely meets the stockings; and, as he wears no pan¬ 
taloons, his flesh about the knees is bare and exposed to the 
cold of his severe climate; and yet he seems to be as com* 

19 


218 


PRACTICAL PHYSIOLOGY. 


fortable as his southern neighbors, whose limbs are more 
carefully protected. 

523. There is a great difference in the habits of clothing 
of individuals. One always wears thick clothing, and from 
the first approach of cold weather in the autumn till the 
warmth of spring, he never ventures abroad without a great 
coat; and if by chance he is compelled to go out without this 
protection, he is chilled, and perhaps disordered; while others 
dress much lighter, and find few, perhaps no days in winter 
so cold as to require any such extra covering. 

524. Some men never wear gloves or mittens; others 
always wear the warmest they can obtain. Some wear flan¬ 
nels next to their bodies; others never wear any. Some 
always put on a tippet to cover the neck in any weather in 
winter, and suffer if they leave it off before the warm season 
returns; others wear only low cravats, or even none, and 
suffer no more. Men wear stout boots and thick stockings 
through the winter, while most women are kept apparently 
warm with worsted or cotton hose, and shoes as thin as men 
wear in the dryest and warmest days of summer. 

525. Thus we see that there is no positive and fixed law 
for the quantity of protection which we should give to the 
external surface. There is a very great difference in man¬ 
kind in this respect, without a corresponding difference of 
health and comfort. This is due, in a great measure, to 
difference of habit of clothing. Men cannot change this 
habit suddenly without suffering; yet, if they do this cau¬ 
tiously and gradually, they may nearly reverse their habits, 
and still retain their health. 

526. Those who accustom themselves to wear but light 
clothing, and exercise actively, in the cold season, acquire 
and maintain the winter constitution. (§ 444, p. 189.) They 
have more radiation of heat outwardly, but they generate 
more heat inwardly to sustain it. But those who are always 
careful to cover themselves heavily, retain partially their 
summer constitution through the winter. Their radiation is 
then increased, but their internal fire does not burn more 


THE SKIN. 


219 


vigorously. They are therefore tender in respect to cold, and 
cannot bear what others do without suffering. An undue 
anxiety to guard against exposure, manifested in excess of 
clothing, frequently disarms one of the natural protection 
against the effects of a low temperature. Those who are 
over-careful to dress warm, and never walk abroad in winter 
without the thickest outer garments for their bodies, over¬ 
shoes for their feet, and tippets for their necks, make them¬ 
selves tender, and are more liable to be affected by changes 
of the weather, and to take cold, than those who clothe 
themselves more judiciously, and develop and depend more 
upon their own internal resources. The very common prac¬ 
tice of schoolboys wearing woollen tippets about their necks 
has caused more sore throats than it has prevented. 

527. Some differ very widely in their habits of dress in 
various periods of life. I know of men who once were ac¬ 
customed to clothe themselves in the warmest woollens and 
furs, and who never went into the open air, in winter, without 
extra garments; and these were doubled in the severest 
weather. In this manner, they became so tender as to suffer 
if they infringed in the least upon their law of habit. But 
these same men, by slow degrees, have left off their extra 
dresses, and now find them to be seldom or never needed. 
They were before so delicate that they felt a chill, or a sore 
throat, or pain in the muscles, or joints, or the lungs, if they 
even entered the street, without a great coat, in cold weath¬ 
er. Now they walk boldly for hours without extra clothing, 
and suffer no bad or uncomfortable consequences. Precisely 
the reverse sometimes happens, and the hardy become deli¬ 
cate from an opposite change of habit. 


PRACTICAL PHYSIOLOGY. 


Sfi 0 


CHAPTER X. 

Those who have poor or insufficient Food, or Dyspepsia, or breathe 
bad Air, need more Clothing. — More Clothing needed in dry and 
windy Weather than in damp and still Air. — More needed in 
travelling than when quiet. — Every one should be clothed com¬ 
fortably.— Hardening. — Old People and Children must be well 
clothed. 

528. The quantity of clothing depends, not only upon 
habit, but upon many other circumstances which are con¬ 
nected with the health, and which affect the generation of 
internal heat, and the healthy actions of the skin. If one is 
not supplied with sufficient fuel for the internal fire; if he is 
ill-fed, and has insufficient or poor food; if he is dyspeptic, 
and his stomach is unable to convert his food into the chyle 
for the blood; if nutrition goes on heavily, and the changes 
of particles are slow; or if he exercises but little, and the 
energies of his life are dormant,—he can bear less expo¬ 
sure unprotected, and he therefore needs more clothing. 

529. Or if the lungs are supplied with insufficient air; if 
one sits in a crowded and unventilated lecture or school room 
for hours; if he ascends to the top of a mountain, where the 
rarefied atmosphere contains a smaller quantity of oxygen; 
or if the chest is encased with tight dress, so that it cannot 
expand and receive sufficient air; or if the lungs are diseased 
and their air-vessels partially closed; if in any way the blood 
receives less than its due amount of oxygen, — then there is 
less heat to be given out, and more protection is required. 

530. If the fuel of good and nutritious food is not sup¬ 
plied for the internal fire, there must be greater external 
fire, or more protection; for then the body cannot sustain the 
loss of so much heat as would pass from flesh at 98° to a 
surrounding atmosphere at the ordinary temperature (65° to 
70°) of comfortable rooms. Insufficiency of food thus cre¬ 
ates a necessity for a greater expenditure for clothing and 
warming. 


THE SKIN. 


221 


*^21. It is manifest, then, that there can be no positive 
and universal law for the quantity of clothing. This must 
be as diverse as are men’s habits, health, and exposures. 
What is enough for one man may be too much for another; 
and what is only sufficient for comfort and for security from 
disorder at one time, or in orfe assemblage of circumstances, 
may be oppressive at another time, and in other circum¬ 
stances. 

532. Dr. Wilson says, “ I have endeavored to establish 
as a law of health the necessity of preserving an agreeable 
temperature of the body.” “ I should wish it to be under¬ 
stood, also, that the feelings, if the nervous system be sound, 
are a proper channel for arriving at a knowledge of the 
state of the warmth of the system.” * It may be said, then, 
in general terms, that every one should wear sufficient 
clothing to make himself comfortable, and to secure his body 
from disturbance of health. More than sufficient clothing 
prevents the free radiation of heat, and causes its accumula¬ 
tion in the skin. The blood-vessels of the surface being 
stimulated to over-exertion, the perspiration is increased from 
the over-action of the blood-vessels, and carries off the sur¬ 
plus heat by evaporation. If a person wears less than this, 
the heat is carried off too rapidly by radiation, and he is 
chilled; the perspiration is checked, the cutaneous blood¬ 
vessels are contracted, the balance of the circulation is dis¬ 
turbed, and internal derangement follows. 

533. In good health, a sudden and momentary chill from 
exposure to cold air, or a cold shower-bath, is not followed 
by these unpleasant consequences. On the contrary, re¬ 
action takes place in the cutaneous blood-vessels, and a glow 
of heat follows; and one is, perhaps, the warmer for this 
sudden transition. But continued cold is injurious both to 
the cutaneous circulation and to the internal health. 

534. There is a great difference in the power of bearing 
cold, which comes from the habit of exposure. The driver 


19 * 


* On the Skin, p. 108 


*222 


PRACTICAL PHYSIOLOGY. 


of a stage-coach sits on his elevated and unprotected seat in 
face of the severest winds of winter, for one or two hours, or 
even more, without apparent suffering, while his passengers, 
less hardy than himself, and perhaps much more heavily 
clothed, are shivering with cold. He has endured this ex¬ 
posure daily through the entife winter, and for successive 
years, and has become hardened; but they have been accus¬ 
tomed to the mild temperature of houses and shops, or, if 
they lived a while in open air, they kept themselves warm 
with active labor. 

535. This coachman is a man of robust constitution; he 
eats heartily and digests easily, and is well nourished. He 
attained gradually to this power of endurance, and now he 
does not suffer. The pilot, the market-man, &c., who enjoy 
equally good original health, and have gone through a simi¬ 
lar training, may bear the cold as well as he does. They 
too are hardened. But more feeble and less active men 
cannot thus expose themselves, without danger. There is a 
common but erroneous notion that any one can harden him¬ 
self by exposure, and become able to endure severe cold 
without much outward protection. I have known some 
sedentary men, whose days were spent in warm rooms 
or shops, attempt to harden themselves by going abroad in 
the winter without outward garments; but they failed to 
accomplish their purpose. They did not begin with slight 
trials, and, proceeding gradually, go by slow degrees from 
small to greater and greater exposures; but they began 
with the greatest. They had not the robust health, the 
hearty appetite and vigorous digestion, nor the energy of 
muscular power, that belonged to laboring men, and con¬ 
sequently they did not generate an increase of internal heat 
to maintain the extraordinary radiation. Instead of return¬ 
ing from their cold walks or rides with a glow upon their 
cheeks, and the flush of ruddy health, they were pale and 
cold. Instead of a reaction afterwards, their cutaneous cir¬ 
culation continued languid, and they were not easily warmed. 
They became more susceptible of cold, rather than mors 


THE SKIN. 


223 


able to resist it, and in some instances their health failed, 
and they sank under the experiment. 

536. More clothing is necessary in infancy and in old 
age , when the generation of internal heat is more feeble than 
in the middle periods of active life. It is a mistake to sup¬ 
pose that infants should be lightly clothed, or that the neces¬ 
sity of warm garments for them is the mere creation of habit. 
They can give out no more heat than is prepared within ; and 
as this is less in them than in others, they cannot bear an 
equal loss without reducing their temperature below the 
natural standard. They must therefore be protected with 
more caution. The same law applies to the aged, and even 
more strictly, inasmuch as their sensations are so blunted 
that they cannot so easily tell when they are cold. And 
oftentimes they are suffering serious disturbance before 
they are aware of it. 

537. It must not be inferred, from the preceding sections, 
that men who are engaged in sedentary employments, or who 
are otherwise than robust, cannot, by discreet exposure, ac¬ 
quire a power to endure the weather of cold seasons. Pre¬ 
cisely the reverse is the fact. But this exposure must be 
just in proportion to the power of the body to bear it, and 
increased only as fast as the energies of the constitution 
increase. It should always be accompanied with so much 
clothing that the body shall not suffer while abroad, and the 
chill must not be so great that reaction will not take place 
immediately after returning to the house. With these pre¬ 
cautions of suiting the exposure to the powers of the consti¬ 
tution, wearing clothing sufficient for comfort, or exercising 
actively enough to sustain the increased demands for heat, 
even the feeble can generally acquire a power to endure 
all the weather of this climate. 


224 


PRACTICAL PHYSIOLOGY. 


CHAPTER XI. 

Clothing should be of loose Texture, and fit loosely to the Body. — 

Various Materials of Clothing. — Linen, Cotton, Silk, Wool.— 

Flannel, next to the Skin. 

538. The great object of clothing being to defend the 
body from cold, by preventing the radiation of heat, the ma¬ 
terials should therefore be bad conductors of heat. This 
non-conducting principle is not so much in the material 
itself as in the air which is retained within its loose textures. 
“ In every case it is the power which the coverings possess 
of detaining atmospheric air in their meshes which is the 
cause of this warmth.” * Clothes of loose and open texture 
contain more air than those which are close and firm, and 
garments that are lined and wadded with very light material 
offer the same advantage of holding layers of air within the 
spaces of their texture. The loose and light kinds of wad¬ 
ding are the warmest, because they afford the largest space 
for air. The old-fashioned bed-quilts, which were made of 
double layers of old and worn woollen cloth, and a small 
layer of wool, very closely quilted, were much cooler cover¬ 
ings than the modern quilts of cotton cloth, with very light 
wadding of cotton or eider down. For the same reason, 
threadbare garments are colder than new, from which the 
nap is not worn off; and those which have a long and 
shaggy nap are much warmer than those which are well 
sheared and nicely dressed. 

539. On the same principle, the garments should be 
made to fit loosely to the body, so as to leave a space for the 
air between them and the flesh. “ Every one is practically 
aware that a loose dress is much warmer than one which 
fits closely; that a loose glove is warmer than a tight one; 
and that a loose boot or shoe is more comfortable in the 
winter than a tight one.” * The loose sack is a warmer 
outer garment than the close-buttoned surtout. If there are 


* Wilson on the Skin. 


THE SKIN. 


225 


several layers of dresses, each one should be considerabl e 
looser than the next one within, so that a layer of air may 
be kept between them. In all these cases, the several strata 
of air between the different garments, and in the meshes of 
the loose textures of cloth, acting as non-conductors, prevent 
the passage of heat. From this cause, the attic chamber, 
which has nothing but the roof between it and the burning 
sun or freezing air, is much hotter in the summer and colder 
in the winter than the chamber below, which has the air 
of the attic between it and the solar rays or the outer 
atmosphere. 

540. The various materials of our garments — linen, 
cotton, silk, and woollen — have different qualities, and are 
consequently suitable for different persons and seasons. The 
fibre of linen is round, pliable, smooth, and soft to the skin ; 
it therefore makes a most agreeable garment. Yet it is a 
good conductor, and allows the heat to pass off rapidly, and 
therefore feels cold when it touches the skin. Moreover its 
fibre is porous, and absorbs and retains the water of perspira¬ 
tion. Water being a still better conductor than linen, those 
who wear this cloth are chilled after sweating, even in a hot 
day. For this reason, linen is more and more abandoned as 
an article for under-wear in hot climates. 

541. Cotton is a worse conductor, and therefore warmer 
than linen. It is also soft, though less so than linen, and 
less pleasant to the touch, for its fibres are not rounded, but 
“ are flat and have sharp edges,” which irritate some delicate 
skins. But it does not absorb moisture, and for this reason 
it is the favorite and proper under-dress of all climates. 

542. Silk is not so good a conductor, and is warmer than 
cotton. Its fibres are round and pliable, and it makes a 
pleasant garment for the skin. It attracts no moisture, and 
gives a sensation of freshness to the surface when it touches 
it. But, “ on the slightest friction, it disturbs the electricity, 
and then becomes a source of irritation,” and in very delicate 
and irritable constitutions it sometimes produces eruptions. 

543. Wool is the worst conductor of heat, and is there 


226 


PRACTICAL PHYSIOLOGY. 


fore the warmest for winter garments. It absorbs no moist¬ 
ure, and defends the wearer from the chills that frequently 
succeed perspiration in a hot but changeable climate. Its 
fibre is porous, and contains minute portions of air, and it 
makes cloth of loose texture. But its fibre is rough and 
scaly, and is very irritating to delicate skins. It also disturbs 
the electricity even more than silk. For these reasons, 
many cannot bear any woollen garment next to their bodies. 
However fine and delicate the fabric, it always irritates them. 

544. It is desirable to guard the warmth of the skin, not 
only from the permanent influence of the atmosphere, but 
against any sudden changes which would produce a chill. 
If our clothing is filled with water, the heat is carried off 
very rapidly, as water is a good conductor. Wool is there¬ 
fore a more appropriate material to be worn next to the skin 
than linen ; and if the garment is made loose, and of fine 
texture, such as thin flannel, it is a great safeguard against 
the effects of changes in hot climates and hot seasons; and 
the feeble and delicate would be safe to wear it at all times. 


CHAPTER XII. 

Advantage of Flannel in hot Climates. — Cutaneous Excretions re¬ 
ceived on the Clothing. — Foul Clothing offensive to the Sense of 
Touch. — Clothing and Beds should be aired. 

545. Dr. Andrew Combe quotes the example of a Brit¬ 
ish ship of war, which, after sailing for two years among the 
icebergs on the coast of Labrador, was immediately ordered 
to the West India station. On this change of location, every 
man was provided with flannel shirts and drawers, which 
they wore while in the hot climate. “ The ship proceeded 
to the station with one hundred and fifty men, visited almost 
every island in the West Indies and many of the ports in the 
Gulf of Mexico, and, notwithstanding the sudden transition 
from extreme climates, returned to England without the loss 



THE SKIN. 


227 


of a single man, or having any sick on board.” The same 
commander had, at another time, the charge of the gun-brig 
Recruit, which lay about nine weeks at Yera Cruz, and used 
the same precautions in the clothing of his crew, and thus 
preserved the health of his men, while the other ships of war, 
which were anchored in the same harbor, and exposed to the 
same influence of climate and labor, lost two fifths of their 
raen* 

546. It should be stated, that this wearing of flannel was 
not the only precaution taken by this provident officer for the 
health of his crew. Every kind of pains was taken to secure 
a dry and pure atmosphere in the seamen’s sleeping apart¬ 
ments; and every means of cleanliness used, so that they 
should neither breathe foul air nor be exposed to foul exhala¬ 
tions from the walls and floors of their rooms. 

547. A commander of a merchantman, who had sailed 
much to St. Petersburg, in Russia, and to the West Indies, 
East Indies, and Brazil, from Boston, informed me that he 
provided flannels as carefully for his southern as for his 
northern voyages, and he found them as effectual a safeguard 
against the diseases of the warm climates as against the 
chills, colds, catarrhs, and rheumatisms of the north. 

548. Those who practise the cold water system in the 
treatment of disease, and who seem to bear exposure to cold 
water and cold air with remarkable ease, discard flannels as 
injurious. But their experiment has not been sufficiently 
tried to establish a universal law. It is therefore safe, at 
least for the old and the delicate, to adhere to their custom 
of wearing flannels next to the skin. 

549. The cutaneous excretions are first received upon 
the clothing, and then a part of them are carried away by 
the atmosphere, and a part of them are retained upon the 
garments. It is easy to perceive this, by seeing the dark 
and dingy color of the white cotton or linen which has been 
worn next to the skin, and so closely covered by the outer 
clothing, that no dust nor dirt could come to it from abroad. 


Combe’s Physiology, Chap. III. 


228 


PRACTICAL PHYSIOLOGY. 


This coloring matter upon these under-dresses could only 
come from the skin. If further proof were needed, notice 
the foul odor, on Saturday, of the inner garments of some 
laborious men, who do not bathe, and who change their linen 
but once a week. 

550. Clothing that is soiled hy being worn next to the 
jlesh is offensive to the touch as well as the sight and the 
smell. Shakspeare makes the merry wives of Windsor, 
when they wished to throw the greatest indignity on Sir John 
FalstafF, put him into a basket of foul linen, which was cov¬ 
ered with the cutaneous excretions of the body. We feel a 
sensation of comfort when we put on clean linen, and of dis¬ 
satisfaction when we put on that which is otherwise. And 
without the aid of the eye or nostrils, the sensitive skin can 
determine whether a garment is pure or foul, when we put it 
on. And, however dark it may be, we can tell by the feeling 
whether our sheets are fresh and clean, or soiled and worn. 
No children are more particular to put off foul clothing and 
put on clean, than the blind at the Institution at South Boston. 

551. To prevent this accumulation of the cutaneous ex¬ 
cretions, which, being retained, become foul and offensive, 
the garments which come in contact with the body should 
be frequently changed and washed. None of the clothing 
of the day should ever be worn in the night, nor ought the 
clothing of the night to be worn in the day. Morning and 
evening there should be a complete change of every article 
of dress; and each garment, when taken off, should be 
separately spread, in order that the air may come in contact 
with all their surface. By this airing, much of the foul ex¬ 
cretions is carried away from them. The clothing which is 
taken off at any time to be reworn should not be hung up 
in a close closet, nor packed in drawers or trunks, until it 
shall have been thoroughly aired by a similar exposure. 

552. That thrifty housewifery w’hich requires the beds 
to be made up in the morning as soon as vacated by the 
lodgers, is prejudicial to health. The beds and bedding 
need airing more than the day clothing. This last is ex- 


THE SKIN. 


229 


posed to some changes of air most of the time while it is 
worn, and a portion, at least, of the excretions is dissipated. 
But as the body, while sleeping, continues in one place, and 
with no change of air through the night, the bed-clothing 
loses none of the animal excretions, and there they remain 
in the morning. The bed, therefore, should be opened, its 
several parts separated, and the mattress, the feather-bed, and 
the under-bed, should be laid apart one from another, and 
the sheets, blankets, and all the other bedding hung on chairs 
or other things which will allow the air to reach both their 
surfaces. And thus should the chamber be left, and the bed 
be aired for some hours each day, with a window open, how¬ 
ever cold the air. 

553. It is an uncomfortable as well as an unhealthful cus¬ 
tom to use the single cabin of canal boats for day as well 
as for night room. There all the work of life is carried on. 
There the passengers sit and eat during the day, and sleep 
during the night. To prepare for lodging, the beds are fixed 
to the walls by means of hooks and ropes, every evening; 
and, in the morning, in order to make room for the break¬ 
fast table, these beds are all taken down and packed in as 
small a compass as possible; without opportunity of airing, 
or any means of purification, they are closely compressed 
through the day, until they are needed again at night. In 
addition to the unavoidable excretions of the present night, 
these beds retain the accumulated excretions of several 
nights, and perhaps of successive passengers during a 
whole trip. 

554. Some dwellings of the poor in cities present the 
same seeming necessity of piling the beds and the night 
clothes into one close heap, to allow room for the day opera¬ 
tions of the family. Press-beds and sofa-beds in sitting- 
rooms, which are shut up immediately after being left in the 
morning, are liable to the same objection. They have no 
opportunity of being aired, and the foul excretions of the 
night are retained during the day, to irritate the skin of the 
lodger when he returns. 

20 


230 


PRACTICAL PHYSIOLOGY. 


CHAPTER XIII. 

Dead Particles of Cuticle are lodged on the Skin. — We bathe the 
Hands and Face, but the Body is not generally bathed. — Those who 
bathe daily have soft Skin. — Bathing a religious Rite in ancient 
Times and in Oriental Countries. — Much practised in Russia and 
Finland. 

555. The cuticle is constantly casting off its outer layers 
in scurf or minute scales. Some animals cast their skins 
entire, and others cast their shells once a year; but man is 
incessantly casting his skin. The outer scales, which are 
the dead particles of the cuticle, lie loosely on the surface, 
and can be scraped off with a knife at any time; they have 
then the appearance of branny powder. Some animals cast 
their hair or shed their coats, and birds moult their feathers 
annually. But the hair and nails of man grow from their 
roots, and thrust out their outer extremities, which, if not 
trimmed, would be continually breaking and dropping off. 

556. If any one who had for a long time deprived him¬ 
self of the needful luxury of a warm bath should remain for 
several minutes in one, he would be surprised to see how 
large a quantity of this accumulated matter of the dead skin 
he could rub off with his hands or a flesh-brush. The re¬ 
moval of this gives to the skin a very agreeable sensation of 
comfort. This is more perceptible after taking a warm 
than a cold bath. 

557. We bathe the face and hands daily, and oftener, and 
know how comfortable the skin upon those parts feels after 
this operation. But if this duty is neglected, the skin is 
irritable and irritated; it seems stiff and loaded, and we feel 
disposed to scratch and rub it to remove the disagreeable 
burden. But the other parts, which are not so frequently 
washed, are not so easily offended. They bear the burden 
of accumulated excretions and dust with less complaint. 
But, if they were cleansed as faithfully as the hands and 
the face, they would be equally sensitive, and feel as keenly 


THE SKIN. 


231 


the comfort of a bath and the discomfort of neglect. This 
sensibility of the skin of the hands and face is a mere mat* 
ter of cultivation, and might as well be cultivated in the 
skin of the other parts which are covered with clothing. 
But those parts which are not exposed to sight are with 
most people rarely, and with some never, bathed; and the 
great majority of mankind leave so much of their surface 
unwashed and untouched with water, from summer, through 
the entire cold season, until summer again returns. 

558. The consequence of this negligence of ablution is, 
that the skin becomes overloaded with the gathered excre¬ 
tions of months and years; it loses its exquisite sensibility; 
it is less able to throw off the waste of the body; the cu¬ 
taneous circulation is not so well sustained; the skin is 
less supple and elastic, and less able to maintain the equi¬ 
librium of heat; and the whole body is comparatively dull 
and inactive. In those who are accustomed to take their 
daily entire bath, the whole skin is soft and elastic; the 
cutaneous waste is carried freely away. They are conse¬ 
quently enabled to bear the heat and cold, over their whole 
frame, with much more ease than others do who wash their 
hands and face alone; and they enjoy a more acute sensi¬ 
bility of skin, a general lightness and buoyancy through 
their frame. 

559. To maintain the most perfect health of the skin 
and of the internal organs , the whole surface should he daily 
cleansed of all its excretions, — the oil, the scales of the cu¬ 
ticle, and the salts of the perspiration, — and also of the other 
matters which lodge on the body and become mixed with 
these. No part should be neglected. Water will remove the 
salts, and soap the oily excretions. Nothing can be substi¬ 
tuted for soap. Some have attempted to use wash-powder, 
and others sometimes use alcohol or spirits; but none of 
these combine with the oily matter, or dissolve the others, 
and cleanse the skin. “ Soap,” says Dr. Wilson, “ renders 
the cutaneous product of the skin freely miscible with water 
and hence it is an invaluable agent in purifying the skin. I 


232 


PRACTICAL PHYSIOLOGY. 


may affirm that it is an indispensable aid ; for in no other way 
can the cutaneous substance, and the dirt which adheres to it, 
be thoroughly removed from the surface.” * No other matter 
applied to the surface will give it the healthy glow, the com¬ 
fortable sensation, and the natural and lively look, and beau¬ 
tiful hue, that are left by soap and water. Various kinds of 
powders are sometimes used upon the face, with the mistaken 
notion of improving its beauty. These mix with the oily 
excretions, and form a pasty compound. They increase the 
burden upon the skin, and impair its vitality, deaden its 
liveliness of expression, and sully the brightness of its color. 

560. Some nations have practised bathing as a religious 
rite. It was a good custom of the ancient Israelites, the 
Egyptians, and the inhabitants of the East Indies, to bathe 
as a part of duty, as typical of moral purification. The 
Greeks and Romans considered bathing so essential, that 
their public bathing establishments were large and magnifi¬ 
cent, and their private baths were as splendid as the means 
of the owners would permit. 

561. The moderns have not improved upon the ancients 
in the care of their skins; nor have the civilized nations of 
Central and Western Europe, and America, improved upon 
the less cultivated Hindoos, Persians, and Turks. The 
Russians and the Finlanders indulge themselves very much 
in this matter, and baths are attached to houses of all classes 
in Finland, Lapland, Sweden, and Norway.t But the Eng¬ 
lish and the Americans do not generally use the bath. 

562. There are various kinds of baths, — the cold and the 
warm, the shower and the vapor bath, — all of which have 
their appropriate uses. The Russians are very fond of their 
peculiar vapor bath. This is one great hall, warmed by 
stoves; large red-hot stones are placed on the stone floor, 
and water poured upon them; the room is then filled with 
vapor heated up to 120° or 130° Fahrenheit. Dr. Grenville 
says he found that the Finlanders, in some instances, sat 
half an hour in vapor baths heated by hot stones to 169° 

* On the Skin. f Bell on Baths, p. 33. 


THE SKIN. 


233 


The bathers, covered with the steam, sit on benches until 
they break out with a profuse sweat. Then they are washed 
with soap suds, and next buckets full of warm water, and 
lastly of cold water, are poured upon the head. Sometimes 
the Russians will run from this steam bath and plunge into 
a bank of snow, and feel no injury; on the contrary, a com¬ 
fortable glow of heat comes from the vigorous circulation, 
which the cold of the snow stimulates.* 


CHAPTER XIV. 

Cold Bathing. — Sponge Bath. — The most Laborious need Daily 
Bath.— Some cannot bear Cold Bath. 

563. If the health is good, and the body is full of animal 
heat, the cold bath answers the purpose of health in summer; 
and if used with energy and perseverance, it is also sufficient 
for winter. It is an excellent habit of some to take a cold 
bath every morning, both winter and summer, not omitting 
it even in the coldest weather. Those who do this find it 
not only very endurable, but they usually enjoy a glow 
throughout all the surface afterwards. So far from suffering 
from cold, the reaction of the cutaneous circulation produces 
an increase of heat, and they are made the warmer by this 
ablution. 

564. It is desirable that every one should be able to take, 
daily, a plunge bath. But this is impossible for all. The 
convenience of a large bathing tub cannot be provided in 
every house. Yet a good substitute is within the reach 
of all. The sponge bath is very easily taken, and requires 
but a very limited and simple apparatus. Provide a large 
wash-bowl and a piece of extra carpet, which should receive 
the drops that fall to the floor, — or, what is much better, a 
large tin basin in shape of a hat, with a shallow crown and 
very broad brim, — and then a soft towel for wiping, and a 
crash towel for friction. These are all that are needed, and 

* Bell, Ghap. II. 

20 * 



234 


PRACTICAL PHYSIOLOGY. 


with these, this very grateful and invigorating ablution can 
always be performed on getting out of the bed. 

565. The cold bath is most conveniently taken as soon 
as one gets out of his bed. It is best to take it when one is 
warm, when there is sufficiency of heat to bear the shock 
and to produce the reaction. This bath should not be so 
long continued in winter as materially to reduce the heat 
and energies of the circulation in the skin; and immediately 
after it the surface should be dried and rubbed until the re¬ 
action commences. The exercise necessary for this rubbing, 
which the bather should do for himself, and the friction on 
the surface, excite the circulation, and produce a very pleas¬ 
ant glow of warmth upon the whole frame. 

566. None need this bath more than the most industri¬ 
ous laborers, who have the greatest demand for their strength, 
and therefore need to take the greatest pains to develop it. 
Yet it is generally urged by them, as a reason for the neg¬ 
lect of this duty, that their avocations allow them no time 
for this, and, however well it may do for the wealthy and the 
men of leisure, it cannot be performed by the poor and labo¬ 
rious, who are always in haste in the morning to go to their 
work. This is certainly a mistake of calculation. The me¬ 
chanic considers no time lost that he devotes to putting his 
machine in good order ; and the wagoner thinks it an advan¬ 
tageous disposition of his time to rub and curry his horses 
faithfully. Both of these believe that they will be enabled to 
accomplish so much the more for this preparatory care. So 
it is with the laborer’s body. In order that it should be able 
to accomplish the most work, it must be put in the best 
working order; and this is done, in part, by cleansing the 
skin of all impurities, unloading it of its burdens, and so pre¬ 
paring it for its functions that its work will not only go on 
well during the day, but contribute its portion to the general 
health and the muscular power. 

567. This cold bathing is a general rule, but not a uni¬ 
versal one for mankind; for some cannot take it with safety. 
If the body is in full health, and the circulation vigorous, — 


THE SKIN. 


235 


if, after the bath, there is reaction and a glow of heat through¬ 
out the surface, — then the cold bath is both safe and useful; 
but if the body is feeble, or the flesh cold, and not easily 
warmed after the bath, or even if the heat does not naturally 
and spontaneously retilrn, then this bath is injurious, and a 
tepid bath should be substituted in its stead. Any one can 
tell, by his own experiment, what temperature he can best 
enjoy, and how great a degree of cold will be followed by 
the comfortable sensation of warmth in his skin. 

568. Even for those who take the daily cold bath, the 
warm bath is occasionally necessary. This is a more ef¬ 
fectual cleanser of the surface. It softens and allows the 
removal of the dead scurf of the skin more readily than the 
others; and for those who do not practise the daily ablution, 
the occasional use of the warm bath, for mere cleanliness as 
well as for health’s sake, should not be omitted. 


CHAPTER XV. 

Effeet of Cold Bathing. — Protects against Cold. — Feeble and con¬ 
sumptive Persons should bathe. — Time for Bathing. — Conditions 
of Bathing. 

569. The effect of the cold bath is not only to invigorate 
the body, and give a tone and activity to both the skin and 
to the internal organs, but it fortifies the skin, so that it is 
better able to endure the exposures to the cold abroad. I 
formerly clothed myself very carefully, seldom went abroad 
without an overcoat in the winter, and often wore a cloak over 
this. Seven years ago, I began the practice of cold bathing, 
and have followed it without intermission since, breaking the 
ice in the coldest weather, and bathing in my chamber, 
where was no fire. I now wear lighter clothing in winter, 
a great coat much less than formerly, and never an extra 
cloak; and, with so much less protection, I suffer less from 
cold than when I was clothed more, but did not bathe. 



236 


PRACTICAL PHYSIOLOGY. 


570. Dr. Andrew Combe confirms this effect of the daily 
coid bath by his own personal experience, and by the ob¬ 
servation of others. “ Instead of being dangerous, it is, 
when well managed, so much the reverse, that the author of 
these pages has used it much, and successfully, for the ex 
press purpose of diminishing this liability, both in himself 
and in others, in whom the chest is delicate. In his own 
instance, in particular, he is conscious of having derived 
much advantage from its regular employment, especially 
in the colder months of the year, during which he has uni¬ 
formly found himself most effectually strengthened against 
the impression of cold, by repeating the bath at shorter 
intervals than usual. Few of those who have steadiness to 
keep up the action of the skin by the above means, and to 
avoid strong exciting causes, will ever suffer from colds, 
sore throats, or similar complaints.” * 

571. For the weakly, — for those who are liable to pul¬ 
monary complaints, who may have any hereditary disposition 
to consumption, or who are subject to rheumatism, — the cold 
bath, or, if this cannot be borne, the warm or tepid bath, is 
one of the means of protection, and should never be omitted 
by people of such tendencies. It should be begun in sum¬ 
mer, and practised, without intermission, through the autumn 
and winter; and the gradual increase of strength and the 
power of endurance will keep pace with the gradual approach 
of the cold season. 

572. It has before been stated (§ 565, p. 234) that one 
should take his bath in the morning, on rising from the bed. 
This is a matter of convenience; for then the labor of un¬ 
dressing is spared, and the means may be ready. This, 
however, is not to be universally practised. To some, — the 
feeble and the debilitated, and to others of peculiar tempera¬ 
ment,— the bath upon an empty stomach, when the system 
wants nourishment from the fast of ten or twelve hours, 
would be injurious. On the other hand, the bath is not the 
safest and best, when taken upon a full stomach, imme- 


Physiology, Chap. Ill. 


THE SKIN. 


237 


diately after meals. For then the cold bath might drive the 
blood too much within, and oppress the stomach, which is 
already excited with the work of digestion; and the warm 
bath, by relaxing the cutaneous vessels, must draw too much 
of the blood outward, when it is needed for the work within. 
In either case, the balance of the circulation is disturbed, 
and the digestion is interrupted. 

573. The best time for the bath is in the forenoon, after¬ 
noon, or evening, when the system is well nourished, and 
the stomach is not full, nor the duodenum empty; never¬ 
theless, the vigorous and robust may take it in the morning, 
before eating, with impunity, and even with advantage. 

574. There is a very common notion that it is injurious 
to go into the water when the body is warm. We have seen 
(§ 562, p. 233) that the Russians go from the hot vapor bath, in 
a profuse perspiration, into the snow. It must not be supposed 
that the case of one of these, heated by the vapor bath, is 
strictly analogous to that of one who is profusely perspiring 
with running or other exercise; and therefore the practice 
which is safe for the Russians in one case, may be unsafe 
for one who is differently heated. Yet the contrary is not 
true. The rule which is often enjoined upon boys and men, 
that, when they go to the river-side or sea-shore to bathe, 
they should first sit on the bank, in the cool air, until their 
temperature is reduced somewhat toward that of the water, 
lest they be injured by the sudden change, is not a good 
one. One should not go into a cold bath when he is already 
co ld — when he has lost so much heat that he can spare no 
more, for any further reduction would be injurious. 

575. The practice of two young men, who, several years 
since, bathed in the Connecticut River daily, during the 
summer and autumn, even through the month of November, 
was contrary to this; and it certainly was successful in their 
case, and doubtless may be in others similarly situated and 
with similar constitutions. They lived rather more than 
half a mile from the river, and fn an elevation from which 
there was a descending slope of about a hundred feet to the 


238 


PRACTICAL PHYSIOLOGY. 


water. As soon as they could see daylight, during the 
colder months of their bathing, they ran down this slope to 
the water’s side, undressed, and plunged in immediately; 
and, after remaining a few minutes, they came out of the 
water, dried, rubbed, and dressed themselves, and then ran 
back to their home, as they said, “ in a delightful glow.” 

576. The same principle directs us to warm ourselves 
well before going abroad in winter. There is no ground 
for fear of taking cold by going from a warm room to the 
cold air, if the body is properly clothed, or if the exercise 
abroad is sufficiently vigorous. The practice of some to 
cool the body partially before going out in the winter, so 
that the changes shall be neither great nor sudden, is alto¬ 
gether needless and unphilosophical. Let one sit for a time 
in a cool room, and reduce his temperature as low as he 
can bear it, without much discomfort, and then go abroad 
into the colder air, and he will begin to suffer much quicker, 
and be much more liable to take cold, than another who has 
been sitting in a well-warmed room, and goes out into the 
cool air, with a comfortable heat upon his flesh. 


CHAPTER XVI. 

Nervous Sensibility increased by Bathing. — Sense of Touch made 
more acute. — Nervous System affected through the Skin. — We 
must aid the Skin in the Performance of its Functions. 

577. Another effect of bathing is to heighten the ner¬ 
vous sensibility. The whole human surface, amounting to 
fifteen square feet, being bespread with the terminations of 
the innumerable nerves, exposes a wider extent of the ner¬ 
vous system to the influence of external substances than any 
other organ; and through this the body receives stronger 
and severer impressions than through any other avenue. An 
injury to the eye, the nose, or the ear, is generally limited 
in its consequences to the injured organ : this may be de- 



THE SKIN. 


239 


stroyed, while the rest of the body remains sound; but a 
burn upon the skin — certainly one that covers the entire 
surface, though not deep, and even slight — is fatal. 

578. If this great extent of skin is covered with the gath¬ 
ered excretions of days, and months, and years, — if its pores 
and its excretory apertures become filled, and the surface 
agglutinated with the compound of perspiration, and oil, and 
dust, — the sensibility of the nervous extremities must be 
blunted, and the power of receiving impressions materially 
diminished. But when the skin is cleansed and unburdened 
of its load of impurities, these nervous points are more free 
to receive impressions, and are more easily acted upon by 
external objects; the skin has then a more lively sensibility 
to pleasure and pain, to heat and cold, and a keener sense 
of touch. The blind would not attempt to read his raised 
letters, nor the draper to discriminate the qualities of cloth, 
with soiled fingers; nor would the accomplished performer 
play on his violin with unwashed hands. 

579. Laura Bridgman, whose senses of sight and hearing 
are lost to her, has a most delicate sense of touch. By 
means of this alone, she perceives the slightest soiling on her 
skin or clothing, and is able to maintain a fastidious neat¬ 
ness of person and dress. Nothing of the kind can exceed 
the purity of her skin, or the acuteness and liveliness of her 
cutaneous sensations. She has, therefore, the nicest power 
of discerning and comparing minute objects. She can, with 
unusual correctness, discriminate the various textures of 
cloths, and distinguish the different degrees of fineness of 
dresses. She enjoys the delicacy of workmanship upon 
wood and metals, and discovers the cleanness and uncleanness 
of her clothing. No one detects more readily any blemish 
upon her garments, and none seems more averse to wear 
unwashed linen, or more desirous to enjoy the change of the 
worn for the fresh dresses from the laundry. 

580. Some produce the greatest effect on the nervous sys¬ 
tem through this avenue of the skin. Esquirol, one of the 
ablest writers upon insanity, and the physician in a very large 


240 


PRACTICAL PHYSIOLOGY. 


Lunatic Hospital in Paris, calms the excitement of the furi¬ 
ous maniac by pouring cold water over the whole surface for a 
considerable period, and, by thus cooling the skin, depresses 
the external nervous system, and, through this, tranquillizes 
the agitated brain. This method is practised with wonder¬ 
ful success in his hands, and is elsewhere found to have a 
similar effect upon many excited patients. 

581. Such is the structure of, and such are the offices 
performed by, the skin. We have seen that the former is 
complicated, and the latter are numerous. It is manifest 
that this whole organ is intimately connected with the oper¬ 
ations of all the other organs, and that the freedom of action, 
the health, and the very life of the inner man, depend very 
materially upon the healthy condition of the outer man. 
We have seen, also, that this organ, while it is ready to per¬ 
form its own part well, cannot do it alone, but stands in need 
of our direction and aid to help it in its work, and our faith¬ 
ful watchfulness to guard it from suffering and evil. 

582. We have therefore a responsibility to sustain in re¬ 
gard to the skin. We must bathe it, and purify it from all 
foulness, and cleanse it from all the excretions that adhere 
to it; we must give it tone and vigor, and power of resist¬ 
ance to external injury, and make it more capable of receiv¬ 
ing impressions and conveying sensations; and, lastly, we 
must clothe it, and otherwise defend it from excessive radia¬ 
tion of heat, and over-active evaporation, which would cool 
the body below its healthy and natural temperature; and yet 
we must not so overclothe it as to lessen its power of self- 
protection. These are duties which belong to every human 
being; for every one is under the same law in this matter; 
all must gain by faithfulness and obedience, and suffer 
from neglect of its requirements. 


BONES, MUSCLES, EXERCISE AND REST. 


241 


PART VI. 

BONES, MUSCLES, EXERCISE AND REST. 


CHAPTER I. 

Bones, Composition of. — Flexible in Childhood. — Brittle in Old 
Age. — Strongest in Middle Life.— Supplied with Blood-Vessels 
and Nerves. — Subject to Growth and Decay. — Grow strong by 
Use. — Should be used cautiously in Childhood. — Rickets. 

583. The bones are hard, stiff, and very strong. They 
are externally solid, but are somewhat hollow within. They 
are composed of such materials, that, without being heavy, 
they are very firm, and formed in such a manner, that, 
without being large or clumsy, they are very strong. The 
composition of the bones is twofold — the earthy and the 
animal. The earthy part of the bones is lime, or rather a 
phosphate of lime. This gives them solidity and firmness. 
The animal part is composed of gelatine, which is a sub¬ 
stance similar to glue. This gives the bones their strength 
and life. Either of these alone would make imperfect and 
weak bones. 

584. When these two elements — the lime and the gela¬ 
tine — are united in due proportions, the bones are very 
strong, and will bear very heavy shocks; but, if either is 
deficient, the body is not supported. When the lime is de¬ 
ficient, the bones will bend; and, when the gelatine is defi¬ 
cient, they will break. We see these different conditions 
of the bones in the different periods of life. In early in¬ 
fancy, the gelatine predominates, and the bones are soft and 
yielding. They are then easily bent, but not easily broken, 

21 



212 PRACTICAL PHYSIOLOGY. 

585. As the child grows, the lime is added, and the bones 
become stronger, until the full maturity of life, when the 
composition is the most perfect and the frame has the great¬ 
est power of resistance, and will bear the hardest blow and 
support the greatest burden without suffering. This state 
continues until the approach of old age. Then the gelatine 
diminishes and the lime preponderates; the bones conse¬ 
quently become brittle, and are more easily broken. 

586. The hones are supplied with blood-vessels and blood; 
they are subject to growth and decay, to deposition 
of new matter and absorption of the old particles, as the 
other textures are. The change is shown in the experi¬ 
ment of feeding sheep with some coloring matter. (§ 248, 
p. 114.) The bones of these animals were red while they 
ate madder, and became white when they returned to the 
usual food of hay and grain. In the first case, the red par¬ 
ticles of the food were deposited in the bones unchanged. 
In the second, these red particles had been absorbed, and 
others, of the natural color, had been deposited in their stead. 
The bones are supplied with nerves, and are therefore sus¬ 
ceptible of pain under some circumstances. In some states 
of disease, the patient complains of pain in his bones. 
When the bone is sawed in amputation, it does not seem 
to suffer; but, if it becomes inflamed, the pain is very 
severe. 

587. When a bone is broken and the parts divided, the 
textures of the severed ends repair the breach. They, in 
the first place, throw out at the broken extremities a quantity 
of adhesive matter. This unites the parts with a soft bond, 
which would prevent their being drawn asunder, but would 
not prevent their bending at this place. After this flexible 
union is formed, the blood-vessels throw into it earthy 
matter, which combines with the jelly, and forms a new 
bone, of composition similar to that of the original bone. 
At first, this new structure is not quite so firm as the old; 
but nature provides for this by increasing the quantity of new 
deposit, and making a bulbous projection all around; thus 


BONES, MUSCLES, EXERCISE, AND REST. 243 

the bone is at the place of junction larger than either portion 
of the shaft, above or below. When, in the lapse of time, 
this new bone becomes condensed, and as strong as the old 
bone, then the external deposit is absorbed, and the whole 
shaft is reduced to its original shape. 

588. The process of absorption and deposition of the par 
tides of bone is shown in their change of shape ; as when 
a tumor or enlargement of the arteries presses upon the ribs 
within, and causes some parts of them to spread; or as when 
the close dresses press upon the same bones without, they 
contract to meet the necessity of the case. (§ 340, p. 150.) 

589. The bones grow larger and stronger by use , like the 
other systems . Exercise of the parts quickens the cir¬ 
culation and increases their nutriment. Disease and inaction 
weakens them. If any one in good health should lie upon 
his bed for a long period, — months or years,— at the end of 
this time he would not find it easy even to stand. The bones 
would not easily support his weight. The exercise of the 
bones favors the deposition of the earthy particles; and for 
this reason the bones of the laborer are dense and hard. 
They have the due proportion of the animal matter and of the 
earthy matter in their composition, and have, consequently, 
great strength. But those who are unaccustomed to labor, 
or even exercise, have not the full proportion of lime in their 
bones, nor the strength that belongs to the working man, 

590. The bones in early life, being more gelatinous and 
earthy, are consequently weak; and the child, although able 
to exercise, is incapable of hard labor. If he is put to hard 
work, the deposition of the earthy matter is hastened, and the 
bones become consolidated before they attain their full size; 
and the boy, not being allowed sufficient time for growth, be¬ 
comes a stunted man. The bones of the child require more 
care for their shape and their growth than those of the man ; 
and if not supported, or if made to bear too great weight, 
they are liable to become distorted. In sitting, the child 
should either find rest for the entire thigh bone, from the hip 
to the knee, upon his chair or bench, or the lower part should 


244 


PRACTICAL PHYSIOLOGY. 


be supported from the knees and the legs by the feet resting 
upon the floor. Too many of the school-rooms are furnished 
with seats built upon one uniform model and of the same 
height. If these are high enough for the older and larger 
children, they are too high for the younger and smaller. 
When, therefore, these sit, the lower leg and foot hang from 
the lower part of the thigh, which projects beyond the seat, 
and may cause it to suffer. (Fig. XXX.) The weak bones 


Fig. XXIX. Fig. XXX. 



of this age do not well bear long continuance of any posture; 
the attitudes, therefore, should be very frequently varied. 


591. This process of consolidating the bones from infancy 
to old age is gradual, and is one of the evidences.of good 
health. But in some feeble persons the lime is not deposited 
in the usual proportion, and the gelatine prevails through life, 
as in childhood; this is the disease familiarly known as the 
rickets. The bones are then weak, and liable to be bent. 
The heads of such bones are generally enlarged and misshapen, 
and the shafts frequently crooked. The spine is curved, and 
sometimes the skull is enlarged. This disease happens mostly 
among those who are badly nourished, who have poor and 
insufficient food, who live in damp and dark rooms or hovels, 
and breathe foul air. 

592. The bones are not solid. Their inner parts are loose 
















BONES, MUSCLES, EXERCISE, AND REST. 245 

and porous, but the external layers are arranged in cells, like 
a honey-comb. This is the most observable in the heads of 
the long bones, as in that of the thigh, (Fig. XXXI.) This 
arrangement gives the bones the greatest strength with the 
least weight. 

Fig. XXXI. Head of the Thigh Bone sawed open. 



a, a, Outer layer of the bone. 

b, b, Inner, or honey-comb structure. 


CHAPTER II. 

Skeleton. — Number of Bones. — Head. — Chest. — Spine. — Verte¬ 
brae. — Cartilages. — Pelvis. 

593. The skeleton (Fig. XXXII.) is composed of two hun - 
dred and forty-six hones , including the teeth and the parts of 
the head. Some of these bones are thin and flat, as the 
shoulder-blade, (Fig. XXXVII.,) and the parts of the head. 
21 # 




246 


PRACTICAL PHYSIOLOGY. 


Some are long and flat, as the ribs, (Fig. XV.) The bones 
of the arms and legs are long and roundish. The vertebras, 
(Fig. XXXIV,) or the parts of the spine, and the bones of 
the wrist (Fig. XXXVIII.) and ankle, (Fig. XL.,) are more 
compact. The bones of the pelvis (Fig. XXXII.) are irregular 

Fig. XXXII. Skeleton. 



a, Head, or cranium. 

b, b , Chest. 

c, c, Back-bone, or spine. 

d , d, Pelvis. 

e, Breast-bone, or sternum. 

/, /, Ribs. 

g, g, Collar-bone, or clavicle. 

h, hy Upper arm-bone, or humerus. 
i y iy Bones of the fore arm. 

ky k, Bones of the hands and fingers. 
I, l, Thigh-bone, or femur. 
m t m, Bones of the leg. 
n, n, Bones of the foot. 


in shape. The bones have various projections, which serve 
for the attachment of the muscles, and apertures for the 
blood-vessels and nerves to pass through ; and all are made 
to fit their places in the structure, and fulfil their purposes in 
the animal economy. 


BONES, MUSCLES, EXERCISE, AND REST. 247 


594. The skeleton is divided into the head , the trunk, and 
the upper and lower extremities. The trunk includes the 
spine, or the back-bone, the ribs, the breast-bone, and the 
pelvis. The head is composed of the eight bones of the skull, 
the fourteen bones of the face, and the six little bones of the 
ears. The eight bones of the skull are arranged to form a 

Fig. XXXIII. Bones of the Head. 


a, Frontal bone. 

b, Parietal or side bone. 

c, Occipital bone. 

d, Temporal bone. 

e, Nasal bone in the nose. 


f Malar, or cheek bone. 

g, Upper jaw. 

h, Thin bone below the eye. 

i, Lower jaw. 


hollow box, to contain the brain. They are united and held 
together by a sort of dove-tailed joint, (Fig. XXXIII.) This 
arrangement and union of these bones give great strength to 
the skull, and enable it to bear heavy blows without break¬ 
ing. The brain has, therefore, a secure resting-place. 

595. The chest is composed of twelve of the vertebrae, or 
bones of the spine, the twenty-four ribs, and the breast-bone, 
(Fig. XV.) The spine or hack-hone is composed of twenty- 
four distinct bones, called vertebrae. Each vertebra consists 
of a body, a ring, and various processes or projections, 




248 


PRACTICAL PHYSIOLOGY. 


(Fig. XXXIV.) These are placed one upon another, from 
the pelvis, at the bottom of the back, to the head, on the 
top of the neck. These bones vary in thickness, from 
about an inch in the loins, to about a quarter of an inch in 
the neck. 

Fig. XXXIV. Vertebra of the JVeck. 
c 

a, Body of the bone, upper surface. 

b, Ring. 

c, Process of bone extending back¬ 
ward. 

d , Front surface of the bone. 

e, e, Processes extending to the right 
and left. 


596. There are seven of these bones in the neck, called 
cervical vertebrce. These are thin, and have long project¬ 
ing or spinous processes extending directly backward, (Fig. 
XXXIV. c.) There are twelve bones in the back, against the 
chest. These are called dorsal vertebrce. They are con- 

Fig. XXXV. Vertebra of the Back. (Side View.) 


a , Body of the bone. 

b, c, Processes of bone extending 
backward. 


nected with the ribs. Their long spinous processes extend 
downward, (Fig. XXXV. c.) The other five are called lion- 




BONES, MUSCLES, EXERCISE, AND REST. 249 

bar vertebra. These are in the hollow of the back, between 
the pelvis and the chest. They are very thick, and have 
short, club-shaped spinous processes, that extend directly 
backward. These processes can be felt through the skin. 

597. Between these vertebrae are layers of very tough and 
elastic cartilage, which adhere very firmly to the bones, and 
hold them together. These layers are very thick in the loins, 
and thin in the neck. They are capable of compression and 
expansion, like India rubber. They may be compressed on 
one side and stretched on the other at the same time. When 
we bow, these cartilages are pressed and flattened on the front 
side, and stretched and thickened on the opposite side. In this 
way, we bend the back in any direction, and the spinal column 
is made exceedingly flexible with this succession of joint?. 
This cartilage is very strong, and capable of sustaining great 
weights. The head, the arms, the chest, and most of the ab¬ 
domen rest upon, and are supported by, the spine. All this 
weight resting upon the back-bone from morning till night, 
while the body is in an erect position, brings so much pres¬ 
sure upon these intervertebral cartilages, especially those at 
the lower part of the spine, that they become somewhat flat¬ 
tened in the course of the day, and thereby the length of the 
spine is diminished, and a man is from a half to a whole inch 
shorter at night than he is in the morning. But as soon as 
the body is placed in a horizontal position, and the pressure 
taken from the cartilages, they begin again to expand, and the 
column recovers its length, and the man regains his ordinary 
height by morning. Nevertheless, the continued pressure of 
the weight of the upper part of the body overcomes, in some 
degree, the elasticity of the cartilages in the course of a long 
series of years, and a man is consequently somewhat shorter 
in old age than in his youth. 

598. The bones of the spine are arranged so as to form a 
column with a double curve , somewhat like the Italic f. At 
its lower end it is curved outward ; as it ascends it is curved 
inward at the loins, and forms the hollow of the back; again, 
it is bent outward at the upper part of the back to enlarge 


250 


PRACTICAL PHYSIOLOGY. 



the chest and give room for the lungs; and, finally, at the 
Fig. XXXYI. neck it is erect. Notwithstanding these 
curves, the top of the spine, the resting- 
place of the head, is vertically over the 
sacrum, on which the last bone of the 
spine rests. This arrangement of the 
bones of the spine gives this column 
great strength and flexibility. 

599. The pelvis forms the base of the 
trunk, (Fig. XXXII.) It is composed of 
three bones — the two hip bones and the 
sacrum, which is apparently a continua¬ 
tion of the spine. These bones are spread 
out to form a sort of basin, on which the 
abdomen rests. The spine stands on the 
sacrum, and the thigh bones are attached 
to the hip bones. 


a, Resting-place of the head. 
a, b, Seven cervical vertebrae. 
c, d, Twelve dorsal vertebrae. 
e, f, Five lumbar vertebrae. 

9, 9> 9 » Spinous processes. 
h, h, Intervertebral cartilages, 
t, Sacrum, a part of the pelvis. 


CHAPTER HI. 

Upper Extremity. — Arm. — Wrist. — Hand. — Lower Extremity._ 

Leg. — Foot. — Arch of the Foot. — Shape of the Foot. — Natural. 
— Deformed. 

600. The upper extremity includes the collar-bone or 
clavicle , the shoulder-blade, upper arm, fore-arm, wrist, hand, 



BONES, MUSCLES, EXERCISE, AND REST. 251 


4 

and fingers. The shoulder-blade or scapula (Fig. XXXVII.) 
is a broad, thin bone, of triangular shape. It lies flat on the 
back of the chest, imbedded in the flesh, and held in its 

Fig. XXXVII. Shoulder-Blade , or Scapula. 


a, Socket for the head of the 
bone of the upper arm. These 
form the shoulder joint. 

by Border of the shallow 
socket. 


place by the muscles. It has no direct attachment to the 
trunk, but at its upper and outer corner it is connected with 
the collar-bone. At this upper and outer corner it has a 
shallow socket for the head of the bone of the arm. 

The collar-bone or clavicle (Fig. XXXII. g , g) extends 

Fig. XXXVIII. Bones of the Wrist. 


a, Radius. 
by Ulna. 

Cy Cy Cy c, Bones of the wrist. 

d, d, dy dy Bones of the hand. 

e, Thumb. 


from the upper end of the breast-bone to the upper and outer 
corner of the shoulder-blade. It keeps the shoulder in its 
place. 




252 


PRACTICAL PHYSIOLOGY. 


The upper arm has a single bone, the humerus , (Fig. 
XXXII.) The fore-arm has two bones, the radius and the 
ulna, (Fig. XXXII.) The wrist has eight bones, (Fig. 
XXXVIII. c, c, c , c,) which are held so firmly together by 
ligaments that they are rarely displaced. The hand is com¬ 
posed of four bones, to which the fingers are attached, and 
the bone to which the thumb is fixed, (Fig. XXXIX.) These 


Fig. XXXIX. Bones of the Hand. 



a, Wrist. 

b, b, Hand. 

c , c , c, c, Fingers. 

d, Thumb. 


are held more loosely together by ligaments, and enclosed in 
one sheath of skin. The fingers are each composed of three 
bones, (Fig. XXXIX. c, c.) The hand is beautifully and 
skilfully arranged and adapted to an almost infinite variety 
of purposes. Its wonderful structure and multiplied uses 
are suited to the exigencies of the mind which directs it, 
and gives to man a superiority over all other animals. 

601. The lower extremity (Fig. XXXII.) is composed of 
the thigh-bone, which is a single shaft, the knee-pan, the two 
bones of the leg, the bones of the ankle, foot, and toes. 
The foot (Fig. XL.) is composed of twelve bones. Seven of 
these bones are of irregular shape, and are arranged to form 
the ankle and the arch, (Fig. XL. a, h, c , d , e,f, g.) The 
other five bones are long. They are joined to the instep 





BONES, MUSCLES, EXERCISE, AND REST. 253 

behind, and support the toes in front. The great toe has two 
bones, and each of the other toes has three bones, corre¬ 
sponding to the bones in the thumb and fingers. 

Fig. XL. Bones of the Foot. 


a, b, c, d, e, f, g, Bones 
joint. 

i, i, Bones of the anteri* 
foot. 

k, Great toe. 

l, l, Other toes. 


602. The arch of the foot extends from the heel to the 
ball, (Fig. XLI.) The bones are exactly adapted to each 

Fig. XLI. Arch of the Foot. (Side View.) 



other, and are held together by ligaments, very firmly, but 

22 






254 


PRACTICAL PHYSIOLOGY. 


not immovably. The arch, therefore, is not unyielding like 
the skull, but it is somewhat loose, and allows a little spring 
to the foot when the body rests upon it. This arrangement 
gives to the foot both strength and elasticity. It admits great 
ease of motion, and saves the jar that would otherwise hap¬ 
pen, when we step upon the ground. The foot rests, not 
upon its whole under surface, but upon the heel and the ball 
near the toes, which are the ends of the arch. The hollow 
of the foot bears none of the weight. The bones of the leg 
(Fig. XLI. a) rest upon the top of the arch, b. 

603. When we step the hollow of the foot upon a round 
stick, so that the ends of the arch do not support the weight 
of the body, as when walking on the round steps of a ladder, 
or when a boy walks on stilts, we feel an unpleasant jar, and 
the want of that elasticity and ease in the step which we 
feel when we walk naturally on a flat surface. When we 
walk, we first place the heel upon the ground ; this receives 
a part of the shock ; next, the ball comes to the ground, and 
the force or weight comes upon the arch. Thus the shock 
is so divided that it is hardly felt. 

604. When we jump down from any high place, we throw 
the toes downward, so that the first force of the blow is re¬ 
ceived upon the ball of the foot. The ankle then bends, and 
the second force is received upon the heel; and again these 
two, being the ends of the arch, yield, and thus the force is 
divided into three portions, and is received in part upon the 
ball, the heel, and the arch; and thus no violent jar is com¬ 
municated to the general frame above. A sailor, falling from 
the mast in a rolling ship, struck the hollow of his foot upon 
the railing, and received a very severe shock and much injury. 
But another, falling the same distance, struck with the ball 
of his foot upon the level surface of the deck, and received 
no great shock and suffered no material damage. 

605. The natural shape of the foot is somewhat broad in 
front, with the toes spread, or, at least, lying loosely, and the 
inner side of the great toe in a line with the heel and the 
ball. The greatest length of the foot is along this line, 





BONES, MUSCLES, EXERCISE, AND REST. 255 

(Fig. XL1I.) This gives to all the bones freedom of motion, 
and to the whole foot its greatest elasticity. But the shoes 
that are usually worn are narrowed in front of the ball of 
the foot, and the toes are rounded, and even pointed some¬ 
times. This shape carries the toes inward from both sides, 

Fig. XLII. Fig. XLIII. 

JKalural shaped Foot . Compressed Foot. 



and causes some of them to override others, (Fig. XLIII.) 
This diminishes the freedom of motion, the elasticity of 
action, and the usefulness of the feet, and creates a limping 
and awkward gait. 


CHAPTER IV. 

Joints. — Hinge. — Elbow. — Knee. —Ball and Socket. — Shoulder. — 
Hip. — Cartilages. — Self-oiling Apparatus. — Ligaments. — Cap¬ 
sules. — Sprains. — Dislocations. 

• 

696. The joints unite the hones together, and yet allow 
them to play upon each other. They are so strong that the 
bones cannot be separated without great violence, yet they do 
not interfere with their motions upon each other. There are 
various kinds of these joints, suited to the wants of the several 
parts in which they are placed. 

The hinge joint allows motion in only one direction, for- 




256 


PRACTICAL PHYSIOLOGY. 


ward and backward, as in the elbow, (Fig. XLIV.,) the knee, 
(Fig. XLVII.,) and the connection of the lower jaw with the 
head. 

Fig. XLIV. Elbow. 



a, Bone of the upper-arm. 

b, e , Bones of the fore-arm. 

c, Inner angle of the joint. 

d, Ligaments of the joint. 


The ball and socket joint is composed of a ball on the end 
of one bone, and a cup or socket in the other, in which the 
ball plays, as in the hip joint, (Fig. XLV. c, c?,) or as the 

Fig. XLV. Hip Joint. 


a, Hip bone. 

by by Thigh bone. 

Cy Head of the thigh 
bone. 

dy Socket in the hip 
bone. 

e, Ligament attached 
to the bottom or centre 
of the socket and the 
head of the thigh bone. 


shoulder, or the attachment of the thumb to the hand. This 
joint allows motion in every direction, forward and back¬ 
ward, upward and downward, and in a circular manner. 

607. The thigh bone has almost a globular head at its 
upper extremity, (Fig. XLV.,) which is fitted into a very deep 





BONES, MUSCLES, EXERCISE, AND REST. 257 

socket in the side bone of the pelvis. The head of the bone 
of the upper arm is less than half a ball, and is fitted into a 
very shallow socket in the upper corner of the shoulder blade, 
(Fig. XXXVII. a.) 

608. The head is connected with the upper vertebra by a 
hinge joint, which allows it to bend forward and backward. 
The upper vertebra has a ring on its posterior side, in which 
a tooth or pin from the second vertebra is inserted. This 
allows the first vertebra to turn upon the second, as a gate 
turns upon a hook-and-eye hinge. By this joint we turn the 
head from side to side, and by the other we nod and lift the 
head. 

The cartilages between the several bones of the spine allow 
the column to bend in every direction. 

609. The head of every bone is covered with a very dense, 
but somewhat elastic cartilage, which is sufficiently soft to 
break the force of pressure or jars upon the bones, but not 
soft enough to be loose and interfere with the movements of 
one bone upon another. These cartilaginous facings of the 
joints are not very thick — not more than a sixteenth or 
eighteenth of an inch. They are covered with an exceed¬ 
ingly smooth lining, that presents the most polished surface 
imaginable. 

610. It is one of the admirable provisions in regard to the 
joints, that they never wear out. Though they are in such 
frequent use, and exposed to so much pressure and motion 
from infancy to extreme old age, even eighty or ninety years, 
yet they never wear out. The tough, cartilaginous coverings 
of the ends of the bones, and the delicate and glairy facings 
of the joints, are as thick and as smooth at the end as at the 
beginning, or at any period of life. These substances, if 
worn at all, are perpetually renewed. They pass through the 
same changes, they are subject to the same death of particles 
from exhaustion, and the same renewal of living particles, as 
the other organs and textures. 

611. Not only do these joints and their parts wear well , 
but they have a perpetual self-oiling apparatus , that keeps 

22 * 


258 


PRACTICAL PHYSIOLOGY. 


their faces always moist and slippery. This is the living 
joint, which prepares and pours out this oily fluid, as the skin 
pours out perspiration; and if the joints are properly used, 
and in good health, this fluid is of the due proportion and 
consistency. But in some cases of disease or injury, it be¬ 
comes abundant, and fills the sac of the joint, as a bladder, 
with water. This happens most frequently in the knee, from 
a blow or a strain. Then this lining membrane takes an un¬ 
natural and increased action, and throws out much more fluid 
than is needed, and so fills the sac of the joint that the knee 
is swelled and lame. 

612. The ligaments and the capsules hold the hones together 
at the joints. The capsule encloses the whole joint: it sur¬ 
rounds the end or the seat of junction of each bone, and is 

Fig. XLVI. Knee , Capsule , and Ligaments. 

a, Tendon of the great muscle of the thigh, 
attached to the knee pan. 

b, Knee pan. 

c, Tendon connecting the knee pan with the 
bones of the leg. 

d, d y Capsule covering all the joint. 

e, f, Lateral ligaments extending from the 
thigh to the bones of the leg. 

g, Thigh bone. 
hy iy Bones of the leg. 

attached to both. In the knee, (Fig. XLVI. d, d ,) the cap¬ 
sule surrounds, and is attached to, the lower end of the thigh 
bone : it passes over the space between the bones, and in like 
manner it surrounds, and is attached to, the upper ends of the 
bones of the leg. The synovial membrane within this cap¬ 
sule prepares and throws into the joint the synovial fluid that 
moistens and oils it. 

There are other ligaments within and without the joints 
Some of those within the knee are seen in Fig. XLVII. The 



BONES, MUSCLES, EXERCISE, AND REST. 259 


wrist (Fig. XLVIII.) and the ankle are supplied with a great 
variety of ligamentous bands, that hold their small bones in 

Fig. XLVII. Knee and Internal Ligaments. 



a, Thigh-bone. 

b, c, Bones of the leg. 

d, e, /, Ligaments connecting these bones 


together. 


their several places, and yet allow them due freedom of mo¬ 
tion. The hip joint has a round ligament, which is attached 
to the bottom of the socket and to the middle of the head of 
the thigh bone, (Fig. XLV. e.) 

613. These capsules and ligaments are strong and inelastic. 
They are so distributed and arranged as to allow all the 
requisite movements, and yet to retain the bones in their re¬ 
spective situations. When they are * exposed to great or 
sudden violence, they are sometimes strained, and some of 
their minute fibres are broken. Then the joint is said to be 
sprained , and requires a long healing process for restoration. 
This happens most frequently to the foot and ankle from any 
misstep or fall, causing a greater strain upon the ligaments 
than they can safely bear. 

614. A bone is dislocated or thrown out of joint when it is 
exposed to still greater strains or violence. The shoulder is 
more liable to this injury than any other joint. The cavity 
is so shallow, that when the arm is stretched forward or back¬ 
ward, and any pressure or blow comes upon it in front or be¬ 
hind, it has little power of resistance, and the head is thrown 
out of its socket. Persons falling forward, as when thrown 



260 


PRACTICAL PHYSIOLOGY. 


from a horse or a carriage, are apt to throw their arms out to 
save themselves; the weight of the body comes upon the 

Fig. XLVIII. Ligaments of the Wrist and Hand. 


a, a, Bones of the fore-arm. 

b, b, by Bones of the hand. 

c, c, c, Ligaments of the wrist. 

d, d, Ligaments of the hand. 


hand, and, of course, upon the arm and shoulder; the force 
of the blow presses the bone backward, and thrusts the head 
over the edge of the socket. 


CHAPTER Y. 

Muscles. — Motive Power. — Number. — Arrangement. — Action. — 
Description and Use. — On Front of the Body. — On Back.— On 
Side. 

615. The bones are merely the framework. They are the 
rigid parts upon which the action is made, but they have no 
active power. All the motive power is in the muscles. These 
perform all the motions in the animal body. 







BONES, MUSCLES, EXERCISE, AND REST. 261 

The muscles form the most abundant part of the body. 
They constitute the great bulk of the limbs, the back, and 
neck. They cover the face and chest, and form the principal 
portion of the walls of the abdomen. In lower animals, they 
are the lean meat which we eat upon our tables. They con¬ 
sist of stringy fibres, that usually lie parallel with each other, 
and are fastened, by a strong whitish-looking substance, into 
bundles. Each bundle, thus fastened together, forms one 
muscle. 

616. These muscular fibres have a power of drawing up or 
contracting, like the earthworm; and when they thus con¬ 
tract, they draw their ends toward each other, and draw to¬ 
gether or move toward each other whatever parts or bones 
may be fastened to these ends. 

617. All the parts of the body that move are furnished with 
some of these muscles , or bundles of lean flesh. There are five 
hundred and twenty-seven muscles in the human body. Five 
hundred and fourteen of these are in pairs, being the same on 
the two sides, and thirteen others are single muscles, as the 
heart, &,c. These are arranged in layers, and in some parts 
of the body, as on the back and the large limbs, there are 
several layers between the skin and the bones. Some of the 
outer layers are shown in Figures XL1X., L., and LI. The 
inner layers are shown in Figures LII., LIV., LV., and LVII. 

618. The cutaneous muscle , (Fig. XLIX. «,) is attached to 
the skin and flesh of the cheek above, and of the neck below. 
It aids in drawing the mouth downward. 

The deltoid , XLIX. 6, or triangular muscle, has its upper 
side, or ends of the fibres, attached to the collar-bone and 
shoulder-blade. These fibres meet in a point, which is at¬ 
tached to the humerus or bone of the upper arm. Its front 
fibres draw the arm upward and forward; its back fibres draw 
the arm upward and backward ; and all, together, lift the arm. 

The biceps , or two-headed muscle of the arm, XLIX. c. and 
LI. b , is attached above to the shou der-blade and the upper 
part of the humerus, and sends a cord to the lower arm near 
the elbow. It bends the elbow. 


262 


PRACTICAL PHYSIOLOGY. 


Fig. XLIX. External Muscles of the front Part of the Bodx,. 



The pronator , XLIX. d , extends from the inner side of 
the arm to the outer bone, and rolls the arm inward, and 
turns the hand downward. 






BONES, MUSCLES, EXERCISE, AND REST. 263 

The supinator , XLIX. d, LI. d , extends from the outer 
side of the humerus and the outer bone of the fore-arm to the 
inner bone; it rolls the arm outward, and turns the hand 
upward. 

The flexors of the wrist, XLIX. f, h, and the long palmar 
muscle, XLIX. g, extend from the lower end of the upper 
arm, and send tendons to the bones of the wrist and hand. 
They bend the wrist. 

The pectoral muscle , XLIX. i, is attached to the breast 
bone and to some of the ribs in front, and extends back to 
the upper and inner part of the humerus. It moves the arm 
forward and upward obliquely. 

The external oblique , XLIX. k , LI. i, arises from the edge 
of eight of the lower ribs, and passing downward and forward 
it covers the abdomen in front, and is attached below to the 
pelvis. It supports the abdomen, and, by its contractions, it 
presses upon its contents and forces them and the diaphragm 
upward in expiration, (§ 286.) 

The semilunar line , XLIX. I , and the linea alba , XLIX. m, 
or white band, are layers of gristly matter extending from the 
breast bone to the pelvis. They give support to the abdom¬ 
inal muscles. 

The sartorius , or tailor’s muscle, XLIX. o , LI. m , ex¬ 
tends from the hip bone over and in front of the thigh, and is 
joined to the inside of the bone of the leg, below the knee. 
It aids in bending the thigh: it rolls the hip joint, and lifts 
one leg over the other, as tailors sit. 

The gracilis , XLIX. q , assists the tailor’s muscle. 

The muscle, XLIX. p, aids in turning the thigh outward. 

The proas and iliac muscles, XLIX. r, w, are attached to 
the back bone, and, passing over the pelvis, are joined to the 
thigh bone. They bend the thigh on the trunk. 

The pectinalis and triceps , or three-headed muscles, XLIX. 
s, t , extend from the front part of the pelvis to the inner side 
of the thigh bone. They assist in bending the thigh, and in 
rolling it outward. 

The rectus , XLIX. w , LI. p, is attached to the front part 


264 


PRACTICAL PHYSIOLOGY. 



Fig. L. External Muscles of the back Part of the Body. 


of the pelvis, and extends along the whole length of the thigh 
bone, and is fixed by a cord to the knee pan. It straightens 
the knee, and lifts the body upon the leg when sitting down. 



BONES, MUSCLES, EXERCISE, AND REST. 265 

The vastus interims and externus, XLIX. v, x , LI. w, 0 , 
are two muscles that are attached to almost the whole length 
of the thigh bone, and send tendinous bands to the upper end 
of the bones of the leg. They assist in straightening the leg. 

619. The trapezius , (Fig. L. a, a, LI./*,) is attached above 
to the head, and the bones of the neck and back : it extends 
outward and part downward and part upward, and its op¬ 
posite end is attached to the collar-bone and shoulder-blade. 
Its upper fibres lift the shoulder; its lower fibres draw it 
downward and backward; and its middle fibres, and the 
whole acting together, draw the shoulder backward. 

The latissimus dorsi , or the broadest muscle of the back, 
L. 6, LI. g, extends from the middle and the lower half of 
the back bone, and the back part of the pelvis, and extends 
forward and upward to the upper arm near the shoulder. It 
draws the arm backward and downward. 

The deltoid , L. c, XLIX. 6, lifts the shoulder. 

The triceps , or three-headed extensor of the fore-arm, L. d, 
is attached above to the shoulder-blade and humerus, and 
below to the extreme point of the elbow. It straightens that 
joint. 

The great gluteus , L. e, LI. Ic , extends from the back part 
of the pelvis to the upper part of the thigh bone. It straight¬ 
ens the hip joint, and raises the body up on the lower limbs 
from the sitting position. 

The biceps , or two-headed flexor of the leg, L. f, is attached 
above to the pelvis and the thigh bone, and sends a tendon 
from its lower end through the outside of the ham to the 
outer bone of the leg. It bends the knee, and its tendon 
forms the outer ham-string. 

The semitendinous and the semimembranous muscles, L. g , 
h , are attached above to the lower part of the pelvis, and, ex¬ 
tending down the back and inner part of the thigh, send cords 
through the middle of the ham to the inner bone of the leg. 
They aid in bending the knee, and their tendons form the 
inner ham-string. 

The gastrocnemius , or great muscle of the calf, L. i, is at- 
23 


266 


PRACTICAL PHYSIOLOGY. 


Fig. LI. External Muscles on the side of the Body. 



tached above to the back of the thigh bone, and, from its lower 
end, sends a tendon to the ankle. It straightens the ankle, 
and lifts the body on the foot. 

620. LI. a. Deltoid , lifts the shoulder. 


BONES, MUSCLES, EXERCISE, AND REST. 267 


b. Biceps , or two-headed flexor of the arm. 

c. Brachial muscle, extends from the middle of the hume¬ 
rus to the front side of the lower arm. It aids in bending 
the elbow. 

d. Supinator , turns the hand upward. 

e. Triceps , or three-headed extensor of the arm. 

f. Trapezius , draws the shoulder upward, backward, and 
downward. 

g. Latissimus dorsi , or broadest muscle of the back, draws 
the arm backward and downward. 

h. Scrratus , or saw-edged muscle. One side has nine 
fleshy teeth, which are attached to the upper nine ribs in 
front: the opposite edge of the muscle is attached to the 
front and outer edge of the shoulder-blade. It draws the 
shoulder-blade forward, and when this bone is fixed by the 
other muscles, it aids in lifting the ribs. 

i. External oblique of the abdomen, aids in expiration. 

1c. Gluteus maximus , or great gluteal muscle, straightens 
the hip. 

l. Gluteus medius , or middle gluteal muscle, extends from 
the back part of the pelvis to the back and outer part of the 
thigh bone. It draws the thigh outward and backward, and 
rolls it outward. 

m. Sartorius , or tailor’s muscle, crosses the leg. 

n. Vastus internus , straightens the leg. 

o. Vastus externus , straightens the leg. 

p. Rectus , straightens the leg. 

q. Tendon or cord forming the outer ham-string. 

r. Tendon forming the inner ham-string. 

s. Gastrocnemius , forms the calf of the leg, and straight¬ 
ens the ankle. 


268 


PRACTICAL PHYSIOLOGY. 


CHAPTER VI. 

Muscles. — Shape. — Attachment. — Situation. — Swell in Action. — 
Arrangement. — Antagonism. — Cooperation. 

621. The muscles are of various shapes, and their fibres 
are arranged in various directions, to suit the wants of the 
places where they are to operate, and the convenience of 
distribution. On the limbs they are long and roundish; on 
the trunk they are mostly flat. Sometimes the fibres are 
arranged in the shape of a fan, the broad end being fixed 
to an immovable bone ; and, at the other end, all the fibres 
are gathered into one point, and are fixed to a movable bone, 
as in the deltoid, (Fig. XLIX. b,) and the trapezius , (Fig. 
L. a,) (§§ 618, 619.) When the fibres of one side of this 
fan-shaped muscle act, they draw the bone in that direction ; 
and when the fibres of the opposite side act, they draw the 
bone in the opposite direction; and when they all act together, 
they draw it in a line with the middle fibres. 

622. The diaphragm (§ 273, p. 124) is a muscle, and 
acts by the same contractile power as the muscles of the 
arms and legs. But, unlike them, it is attached to no joint, 
and moves no bone. It is fixed to the bottom of the ribs, 
and is arched up into the chest. (Fig. XVII.) Its fibres, 
like the spokes of a wheel, extend from the circumference 
to the centre ; and, when they contract, they draw the centre 
and the whole arch downward towards the line of attach¬ 
ment of the outer edge. This descent of the arch leaves 
room in the chest for the expansion of the lungs and the 
inspiration of air. The heart (§ 206, p. 94) is a hollow, 
muscular bag; when its fibres contract, they lessen the cavity 
within and expel the contents of blood. The muscular coat 
of the oesophagus, (§ 23, p. 17,) the stomach, (§ 28, p. 20,) 
and of the alimentary canal, winds about them, and is 
attached to no fixed point. It presses upon the contents of 
these organs, and aids the digestive operation in the stomach, 
and carries the contents onward through the channel. 


BONES, MUSCLES, EXERCISE, AND REST. 269 

623. These muscles, distributed and arranged in nature’s 
most skilful and benevolent manner, are the source of all 
our power of motion. By these we walk, we lift, we strike, 
we eat and swallow, we breathe and cough, we speak, wink, 
nod the head, bend the back, and do all our work. A pal¬ 
sied limb, whose muscular power is lost, is as motionless as 
the limb of the dead. 

624. The muscles are mostly attached to different bones 
at their two ends, and by their contractions move these bones 
on or toward each other, as at the joints. But some muscles 
are intended to move only the flesh, and are, therefore, 
attached only to the flesh, at least at one end, as in the face. 

Fig. LII. Muscles of the Face. 


a, Frontal muscle, raises the 
eyebrows, and wrinkles the fore¬ 
head. 

b , b, Circular muscles, close 
the eye. 

c, d, Muscles that raise the 
comers of the mouth. 

e , Circular muscle, closes the 
mouth. 

/, /, Muscles that draw down 
the lower lip. 


The muscles (Fig. LII. «, a) that wrinkle the forehead and 
draw up the eyebrows, are attached to the bone above, and to 
the skin and flesh below. The muscles that raise and draw 
down the corners of the mouth and the lips (Fig. LII. c, d,f) 
are attached to the bones of the two jaws and the cheek by 
one end, and to the lips by the other. The muscles of the 
eye ball (Fig. LXVI1I.) are fixed by their inner ends to the 
bone within the socket of the eye, and by their outer ends to 
the ball. By their various contractions they roll the eye. 
23 * 



270 


PRACTICAL PHYSIOLOGY. 


Some are circular, as those that close the mouth and eye, 
(Fig. LII. 6, e.) The heart has no attachments ; it is sus¬ 
pended in the chest, and acts only on its contents. The 
muscular coat of the oesophagus, stomach, and alimentary 
canal surrounds these organs, and, by its contractions, it 
forces their contents onward. 


625. The muscles are not placed 


directly between the bones which are 
to be moved,— this would make the 



joints clumsy, — but at some little dis¬ 


tance, and attached directly at one 
end to one bone, and then generally 
fastened to a tendon or cord which 
moves over the joint to the other bone. 
The muscle that bends the elbow (Fig. 
LIV. d) is placed entirely on the front 
part of the upper arm. The upper end 
of this is fixed to the upper bone, but no 
part of the muscle touches the lower 
arm. A cord passes from the lower 
end, over the elbow-joint, to the lower 


arm. So, also, the muscles that move 


the hand, the knee, the foot, &c. 


Sometimes the muscle is placed at a 


considerable distance from the bone 
to be moved. The muscles of the 
fingers are placed, not on the hand, 
nor even on the wrist, but on the 
fore-arm, (Fig. LIIT. a, a, a;) and 
the long cords or tendons (6, b , b) 
can be easily felt as they pass along 
the lower part of the fore-arm, and 



wrist to the hand and fin¬ 
gers. 


b, b, b. Tendons of these ment, the toes are moved by muscles 
muscles passing over the situated on the leg. The cords pass 

Wrist tn tinn/d £v. , * 


through grooves or pulleys at the 






BONES, MUSCLES, EXERCISE, AND REST. 271 

ankles, and there change their direction and pass to the 
toes. 

626. When the muscles draw up, they increase in size, and 
swell out at their middle; and when they cease to act, they 
are again drawn out in length, and their size is reduced. 
If we place the right hand on the front of the left upper arm 
when we bend the left elbow, we shall feel the biceps muscle 
(Fig. LIV. c, d) swelling out and becoming hard. If, at the 
same time, we place the fingers in the angle of the elbow, 
we shall feel the cord drawn tight and moving. If we 
put the hand on the same place when we straighten the 
elbow, we shall feel the muscle growing soft, the swelling 
going down on the upper arm, and the cord moving back¬ 
ward and becoming loose in the elbow. 

Fig. LIV. Flexor Muscle of the Elbow. 



a, Humerus, or bone of upper- 
arm. 

b, Bone of fore-arm. 

c, Hand. 

d, Biceps muscle. 

e, Its upper attachment. 


f y Its cord attached to the lower 
arm. 

g, Muscle that straightens the 
elbow. 

hy Its attachment to the elbow. 


627. The muscle on the back of the upper arm that 
straightens the elbow is broader and larger, so that its swell¬ 
ing and reduction are not so perceptible as in case of the 
bending muscle. Nevertheless, its action and relaxation 
may be perceived, when the lower arm moves upon the 





272 


PRACTICAL PHYSIOLOGY. 


upper. The same action may not only be very distinct¬ 
ly felt, but even seen, on the temple, in the muscle that 
closes the jaw. The upper end of this muscle is fixed upon 
the bone of the temple, and passes down behind the project¬ 
ing arch of the cheek-bone to the upper side of the lower 
jaw. When it contracts and draws up the lower jaw, it 
swells out on the temple so prominently that its increase and 
diminution are seen every time we move the jaw, either in 
mastication of food or talking. 

628. The muscles have only a power of contraction. 
They have no active power of forcible expansion. They 
can draw the bones together, but they cannot push them 
apart. The muscles that bend the wrist or the ankle can¬ 
not straighten it out again. But nature has made beautiful 
provision for this, by affixing to every joint two or more sets 
of muscles for the various kinds and directions of motion 
required. Upon the hinge-joints there are two sets, one 
to bend, the other to straighten them. Thus the muscle on 
the front of the upper arm bends the elbow, and the muscle 
on the back of the upper arm, straightens it. The same ar¬ 
rangement is found in the muscles that move the wrist, the 
fingers, the knee, the ankle, and the toes. 

629. It is interesting to see this antagonism of muscles, 
and their alternate working in the movements of the fingers. 
If we clasp the right fore-arm, at its largest part, three inches 
below the elbow, with the fingers and thumb of the left hand, 
and then drum rapidly with the fingers of the right hand, we 
shall feel the swelling and decline of the muscles on the 
opposite sides of the arm, alternating with each other, and 
precisely corresponding with the motions of the fingers. 
While the fingers are bending, the inside muscles swell and 
the outside muscles decline; and, while the fingers are 
straightening, the outside muscles swell and the inside mus¬ 
cles decline. The same alternation may be felt in the 
movements of any other joint. 

630. The hinge-joints want two sets of muscles only — 
one to bend, the other to straighten But some other joints 


BONES, MUSQEES, EXERCISE AND REST. 


273 


are not limited to this single line of motion. The shoulder 
not only bends forward and backward, but upward and down¬ 
ward ; and it can move in any direction, even round like the 
spoke of a wheel. It would seem necessary, then, that there 
should be many sets of muscles to produce this great variety 
of motions. The ball and socket joints are supplied with 

Fig. LV. Internal Muscles of the Back , Shoulder , and Hip. 



a, Muscle that lifts the shoulder- 
blade. 

by Raises the arm. 

c. Rolls the arm outward. 

d, e, Rhomboid muscles, draw 
the shoulder-blade upward. 


g, Serratus, attached to the 
back-bone and the ribs, draws 
the ribs down. 

h, Straightens the hip joint, 
and rolls the thigh outward. 

iy Elevates the ribs. 


many muscles, (Fig. LV.,) which act individually, succes¬ 
sively, or in combination, and produce every variety of 
motion ; by these we move the arm, the fhigh, the wrist, and 
the thumb in any direction which we may desire. 







274 


PRACTICAL PHYSIOLOGY. 


CHAPTER VII. 

Bones are Levers; Muscles are moving Powers. — Muscles act at 
Disadvantage. — Power sacrificed to Convenience of Action.— 
Especially in the Fingers and Toes. — Muscles cooperate to pro¬ 
duce one Motion. — Rapidity and Precision of Muscular Action. 
— Illustrated by Piano-Forte Player. — Violinist. — Writing.— 
Carpenter. 

631. Those muscles which are situated at a distance 
from the object to be moved work at great disadvantage. 
If that muscle which bends the elbow were placed in the 
bend of this joint, and its lower end attached to the lower 
end of the fore-arm (Fig. LVI. b) instead of the natural posi¬ 
tion at the elbow, it would act with more power than it now 


Fig. LVI. Upper Arm Biceps misplaced. 



a y b , Biceps attached to wrist. 


does. But muscles so situated would interfere very much 
with the freedom of the movements, and with the application 
of the limbs to a great variety of purposes, and be very 
awkward. 

632. In motion, the bones are levers, and the muscles 
are the moving powers. The bones of the fore-arm are 
fixed very near its end, to the extremity of the bone of the 
upper arm. The upper bone is the fulcrum or point of 
support; the muscles that move this lower arm are at¬ 
tached to it within less than half an inch of the fulcrum, 
while the whole bone or lever is ten to twelve inches in 





BONES, MUSCLES, EXERCISE AND REST. 275 

length. Consequently, the muscles act with a disadvantage 
of twenty or twenty-four to one. 

633. Nature makes sacrifice of power to convenience 
of motion, to grace of structure, and to beauty of limb. 
The muscles are therefore made very powerful. When we 
lift a pound in the hand, and bring the fore-arm to a hori¬ 
zontal position, the muscle bending the arm exerts a force 
which would lift twenty or twenty-four pounds, if it were 
attached to the point where the weight rests. When a 
strong man lifts fifty or a hundred pounds with his hands, 
holding the fore-arm in a horizontal position, the muscle 
that raises the arm exerts a force equal to twenty or twenty- 
four times that which would be necessary to lift the same 
weight if it were fixed directly to the weight. 

634. The muscles that straighten the ankle, and raise 
the body upon the toes, act with the same disadvantage 
upon the short end of the lever. The ankle is the fulcrum, 
the whole foot the lever, the heel the short arm, and the foot 
in front of the ankle is the long arm. It is plain that the 
power required to move the foot by the heel must be as 
much greater than that which could move it by the toes as 
the anterior part of the foot is longer than the heel, which 
is about twelve to one. 

635. Muscular contraction is effected with rapidity — 
in some cases, almost instantaneously. This is seen when 
the musician executes rapid pieces of music on his flute; 
for every note that is made includes two motions of the 
muscles on the fore-arm — one to lift, and the other to 
carry down the fingers. It is an established fact, that some 
persons can pronounce distinctly fifteen hundred letters in 
a minute. The pronunciation of every one of these letters 
must require a distinct and double action of the muscles 
connected with the voice and enunciation, for each action 
includes both the contraction and the relaxation. Here are, 
therefore, three thousand actions in one minute. Insects 
exceed all other animals in the rapidity of their muscular 
motions. It is calculated that, with their wings, they strike 


276 


PRACTICAL PHYSIOLOGY. 


the air, not many hundred, but even many thousand times a 
second. 

636. These muscles work in concert, and produce, by 
their cooperation, just the motions that are required. It is 
wonderful to see how exact is this harmony, and with what 
precision is the power measured from, and exertion made 
by, each one in creating any motion. We lift the hand to 
the chin, then to the mouth, then to the nose, to the eye, 
and to the forehead. In each of these motions, there is a 
combination of several or many muscular actions; each- 
muscle and each fibre pulls just so much as, and no more 
than, is necessary to carry the hand exactly to the place 
appointed. A very slight change of force of one of the 
muscles in the shoulder carries the hand from the mouth 
to the nose, and from the nose to the eye, or lets it fall upon 
the breast. 

637. Performers on the piano strike the varied notes 
with equal precision; — first a , then b, then c sharp, then 
an octave, or a fifth, or a third. In all these changes, the 
hand moves half an inch, quarter of an inch, four inches 
and one half, six inches and a quarter, — whatever distance 
is required, it moves just so much and no more,— and hits 
the exact note. This is done by the muscles of the shoul¬ 
der, elbow, and the wrist, — all in harmonious cooper¬ 
ation. However small an extent of contraction of the 
muscle at the shoulder, at the short end of the lever, 
is needed to carry the hand a quarter of an inch to the 
right or to the left, just that extent, that hair-breadth of 
contraction, is made, — no more, no less, — and the unerr¬ 
ing finger hits the note. 

638. The complete government of the muscular action 
is still more remarkably manifested in the skilful violinist. 
He determines his notes by touching the tip of his finger 
on the strings. If he touch them a little higher or a little 
lower, he varies the note. The most accomplished players 
acquire such exact control and discipline of the muscles 
of their fingers, that they can produce at will the minutest 


BONES, MUSCLES, EXERCISE, AND REST. 277 

shades of difference of sound. To produce the precision 
of motion in the ends of the fingers, the muscles that move 
them must contract with still greater precision, without 
varying a fraction from the required amount of motion. 

639. One more illustration forces itself at this moment 
upon me as I write these w r ords. I carry my pen through 
the shape of these letters by means of the muscles of the 
thumb and fingers, and of the arm and shoulder. These 
combine their actions, and carry the pen now up, now 
down, in straight or curved lines, forward and backward. 
They make the exact contractions that are needed. The 
slightest variations of these contractions make an e in¬ 
stead of an i, a d instead of an a; yet these mistakes are 
not made, but the letters are formed in the exact shape that 
is required. 

640 This control over muscular action enables the 
painter, the draughtsman, and the engraver, to produce the 
very pictures which they desire, and the mechanic to use 
his tools, not only with exactness, but with safety to himself. 
When a carpenter is cutting with a broad-axe, upon a small 
block, which he holds with his left hand, he strikes boldly 
and accurately. But a very slight difference of the con¬ 
traction of the muscles of the shoulder that bring the upper 
arm downward and forward would carry the axe upon the 
fingers, and not upon his block. When driving nails, he 
holds the nail between the thumb and finger of the left 
hand, while he .lifts the hammer with the right. He hits 
the nail upon the head; and yet how exceedingly small a 
variation of the muscular contraction would carry the ham* 
mer upon the thumb or the finger, and not upon the nail! 

24 


278 


PRACTICAL PHYSIOLOGY. 


CHAPTER VIII. 

Strength of Muscles not always dependent on Size. — Strength differs 
in various Animals, in Man and Insects, and in various Men. 
— Exercise of Muscles increases their Size and Power. — Muscles 
in Limbs that are exercised stronger than those that are not used. 

641. Muscles are , in general , strong in proportion to 
their size; hut this is not a universal law. Birds are very 
strong, but they have not very large muscles. These would 
add to their weight, and be very inconvenient for flight. On 
the contrary, fishes have large muscles, yet are not very 
strong. Living in the water as they do, which is nearly as 
heavy as themselves, great bulk is no impediment. They 
move about as well with a large as with a small mass of 
flesh. 

642. The difference of muscular power in different 
classes may be shown by comparing man with some in¬ 
sects. A man must be more than usually active to be able 
to jump his own height. A man of ordinary strength can 
hardly lift more than twice his own weight; one of the 
strongest men on record could lift eight hundred pounds. 
But insects have astonishing strength of muscle. A flea will 
leap sixty times its own length, and one of the beetles can 
support uninjured, and even elevate a weight equal to five 
hundred times that of its own body. If a man were strong 
and active in the same proportion, he could jump three 
hundred and forty feet, or more than twenty rods, and lift 
about three and a half tons 1 weight. 

643. Among animals of the same kind, especially among 
men, it may be safely considered that the muscular power 
corresponds with the size of the muscles. Though all men 
are endowed with the same muscles, and these are arranged 
in the same manner in all, yet it is manifest that all men are 
not equally strong, and that their strength is not distributed 
in the same proportion over the various parts of the body, 


BONES, MUSCLES, EXERCISE, AND REST. 279 

One man is very powerful, another is very weak; one is strong 
in the arms and weak in the legs, while another is strong in 
the legs and weak in the arms. 

644. This great and almost infinitely varied muscular 
power is given to men and animals for action. It was no 
intention of the benevolent Creator that this should remain 
dormant. Some of the involuntary muscles work inces- 
santly; day and night, asleep or awake, from birth to 
extreme old age, the heart beats, and the chest moves, and 
the digestive organs carry on their operations and find no 
rest; nor yet are the muscles which perform these labors 
exhausted or even weary. It is the design of our being that 
we use the muscles that are put under our control, arid, by 
their action, both procure our subsistence and sustain our 
health. These two ends are attainable by the same means, 
and are made to correspond with each other. 

645. Exercise of the muscles increases the waste of their 
dead particles , (§ 252, p. ] 15,) and consequently the demand 
for nutrition. The arteries then act more vigorously, carry 
more blood, and deposit more new particles. The active 
muscle, being better nourished, is composed of fresher 
atoms, and has more strength. When this exercise is ju¬ 
diciously taken, neither too little nor too much, the nutrition 
exceeds the absorption, more new atoms are brought than 
old carried away; then the muscle grows larger, and more 
dense and powerful. We find proof and examples of this 
too frequently to escape notice. The mu^les of the inac¬ 
tive, those who neither labor nor exercise, are small, soft, 
and flabby, and hang loosely on the bones; consequently, 
they are weak. But the muscles of the active and laborious 
are large and firm; they are full and very strong, and en¬ 
dowed with great energy of action. 

646. The robust and healthy laborer exercises his limbs 
and his trunk, and consequently has strong muscles. He 
can take his scythe and mow from morning till night, and 
follow this from Monday till Saturday; he can lay stone 
wall or cut wood with the same perseverance; and he does 


280 


PRACTICAL PHYSIOLOGY. 


all this without any great fatigue. But let a student, whose 
arms are unaccustomed to labor, and whose muscles are 
therefore soft, small, and feeble, undertake to do either, and 
he will, in a few minutes, be exhausted. 

647. The student is not necessarily weak in body. If he 
is faithful to the laws of health, and takes daily exercise to 
a suitable degree, his muscular system is sufficiently de¬ 
veloped, and he is strong enough for the support of health, 
though he may be much weaker than the farmer. He can 
walk several miles. He can do the work of gardening, rake 
hay, or perform the lighter labor of farming for an hour or 
two, without much fatigue. The muscles of the inactive 
and indulged girl, who has been taught that exercise — how¬ 
ever useful to the laborer, and proper for men and boys — is 
not requisite for her delicate frame, are soft, like those of a 
babe, and not much stronger. If she attempts to walk a mile, 
she will fail of accomplishing her purpose, or suffer from 
fatigue, perhaps from exhaustion. 

648. Exercise develops the form and the strength of the 
muscles which are called into operation. In order that the 
whole should be developed and strengthened, this exercise 
should be so varied as to use every one of them. The 
farmer is at one time cutting wood, and thereby using the 
muscles of the arms and shoulders; at another, laying stone 
wall, with the muscles of his arms, shoulders, and back; at 
another time, he is ploughing, and using the muscles of his 
arms, back, and*legs; sometimes pulling, sometimes push¬ 
ing, lifting, striking, treading; and in all these ways calling 
every muscle into action. His muscular energies are, con¬ 
sequently, universally developed, and he is strong in all his 
frame beyond other men. There are other occupations that 
have nearly the same effect, but none that give the variety 
of exercise and universality of muscular power that comes 
from the cultivation of the earth. 

649. All employments that call for the use of only a part 
of the muscles, but not the whole, develop the size and the 
strength of those' that are used more than the others. So 


BONES, MUSCLES, EXERCISE, AND REST. 2S l 

vve find some men are very strong in some of their limbs, 
and weak in others; and these strong and weak parts differ 
according to the habits and employments of the people. A 
sailor uses his arms more than his legs. He pulls ropes, 
and lifts the anchor, but has little opportunity of walking. 
Consequently, the muscles of his arms and shoulders are 
large, strong, and hard, while his legs are smaller and 
weaker than those of other men. The blacksmith uses the 
same muscles, and has the same muscular development of 
his arms, and comparative weakness of his legs. The pe¬ 
destrian and the dancer have large and strong muscles of 
the lower limbs, while their arms are comparatively small 
and feeble. 

A similar difference of muscular development is manifested 
in the porter. His employment calls for the exercise of the 
muscles of the back more than that of other men. He car¬ 
ries his burdens on his head or his shoulders. It is necessary, 
therefore, for him to keep his spine erect by the constant and 
vigorous action of the muscles of that region. They, there¬ 
fore, are used more, and grow larger and stronger, than the 
spinal muscles of men who are otherwise occupied. 

This law of special muscular development from special use 
affects the lower animals as well as men. Hence we find in 
them a growth and an increase of power in the muscles that 
are used, and a comparative smallness and weakness in those 
that are not used. The wild birds use their wings mostly for 
locomotion. They sustain themselves very long in the air, 
and fly great distances. They have, therefore, very large and 
strong muscles on their breasts and wings. And, as they 
walk but little, the muscles of their legs are comparatively 
small and weak. 

But the domestic fowls seldom fly; they use their legs 
mostly for locomotion. They have, therefore, much smaller 
muscles on their breasts and wings, and much larger on their 
legs. This difference is, perhaps, the most remarkably seen 
in the wild and domestic turkeys and geese. 

24 * 


282 


PRACTICAL PHYSIOLOGY. 


CHAPTER IX. 

Some Muscles strong and others weak in the same Person. — Ameri* 
can Women walk little. — Muscles become weak by Disuse. — 
Whole System made stronger and more lively by muscular Exer¬ 
cise. This aids Digestion, Respiration, Circulation, and increases 
animal Heat. 

650. The muscles being thus unequally used, and their 
strength unequally developed, in the same person, he may 
then be very strong in one part, and weak in another. The 
sailor or the blacksmith would be wearied with a walk of a 
few miles, while the pedestrian might not be able to carry 
the porter’s burden, and the porter would soon be exhausted 
with swinging the scythe or the sledge-hammer. 

651. Many women, however industrious at home, are not 
generally accustomed to much exercise abroad. Their mus¬ 
cles of locomotion, being little used, are neither large nor 
strong. They cannot move with a vigorous gait nor with an 
elastic step. They walk with so little ease and energy, and 
are so soon fatigued, that they find very little inducement to 
go any considerable distance on foot. Many who can spin 
and weave, wash, make butter and cheese, and perform all 
sorts of even the hardest household labors, without any great 
weariness, are overcome by a short walk. 

I once well knew an elderly lady, an unusually indus¬ 
trious and healthy wife of a farmer, in a country town 
of Massachusetts. Few women were more faithful and 
energetic in the management and labor of the house. Noth¬ 
ing was too hard for her strength, no household work was 
too great for her energy; all the domestic avocations, in 
their due course, were her ordinary exercise. But she 
never walked abroad. She lived about a mile from the vil¬ 
lage and the church, and went to these very frequently, on 
business or pleasure, and for worship. But she had always a 
horse and chaise at command, and always rode; and she in- 


BONES, MUSCLES, EXERCISE AND REST. 283 

formed me that, for near forty years, she had not walked 
from her house to the village, nor did she think that she 
had strength to do it. 

652. The strength and size which the muscles gain by 
exercise are to be preserved by the same means. If suffered 
to remain inactive, they lose their fulness and power, they 
shrivel, and become soft and feeble. Whatever may be the 
cause of the disuse of the limbs, these consequences of waste 
and weakness must follow. An active and strong man re¬ 
ceives an injury, perhaps a cut on the foot. This wound, 
without producing any general disease, may lay him up, and 
keep him still for some months. When his wound is 
healed, he finds his legs are weak, and unable to do their 
former labor. 

653. Dr. Reid cut the great nerve that went to one of 
the legs of a rabbit. The limb was immediately palsied, and 
could not move. In seven weeks he killed the animal, and 
compared the muscles of the palsied leg with those of the 
opposite and sound one. They were paler, softer, and 
smaller, and weighed only about half as much as those of 
the other limb. The bones, also, of the inactive leg were 
diminished in size. So the muscles of the paralytic man, 
who does not and cannot walk, become shrivelled and weak. 
Mr. J., in consequence of an injury, has not been able to 
bend the foot on the leg for more than sixteen years. The 
muscles which formerly lifted his foot, not having been used 
for so long a time, are now shrivelled, and much smaller 
than in other men of his size. 

654. Exercise not only invigorates its own apparatus of 
motion, but it contributes to the strengthening of all the 
other systems, and aids them in the performance of their 
functions. The man of active habits of body has a better 
appetite and digestion and is better nourished, he breathes 
more freely, he has a freer circulation of the blood and a 
clearer brain, than the inactive and the sluggish. The la¬ 
borer, the farmer, the active mechanic, and sailor, seldom 
complain of want of appetite or of indigestion. They work 


284 


PRACTICAL PHYSIOLOGY. 


hard and eat heartily. Their food gives them a comfortable 
sensation, and they are well nourished. But the student, 
the clerk, the watchmaker, the engraver, all men engaged 
in sedentary employments, and men and women of no 
occupation, often complain of failing appetite and weak 
digestion. If they eat heartily, they feel now and then dis¬ 
tressed after so doing, and give painful evidence that if a 
man do not work, he cannot eat satisfactorily. The food that 
the inactive eats, gives him neither the nourishment, nor 
the elastic energy, nor the pleasurable sensations, that it does 
to the man of more active habits. 

655. So closely is use of the muscular system connected 
with appetite and digestion, that exercise is usually one of 
the first means advised for their restoration when they are 
impaired ; and thus we see dyspeptic students leaving col¬ 
lege, and dyspeptic sedentary men giving up their busi¬ 
ness, and betaking themselves to travelling, to farming, or 
some other active employment, as the best method of regain¬ 
ing their lost health. But if the amount of exercise which 
the invalid takes as a means of recovery had been distributed 
through his previous days, and mingled with the hours of 
study and sedentary occupation, very probably it would have 
saved him from his present suffering and indigestion. 

656. When we run, or walk, or labor in any way, the 
heart beats more rapidly than when we are at rest. The 
blood is carried, not only more frequently, but in larger 
quantities, through the muscular system, and through the 
whole frame. The alternate swelling and decline of the 
muscles, in their contraction and relaxation, press upon the 
veins, and force the blood out of them; and, as the valves in 
the veins do not permit this blood to go backward, it must 
go onward toward the heart. This is especially seen in the 
process of bleeding from the arm, when the patient holds a 
cane or ball in his hand, upon which he presses and re¬ 
laxes his fingers in rapid succession. This action swells the 
muscles on the arm, the swelling presses upon the veins, and 
forces the blood onward and outward through the aperture. 


BONES, MUSCLES, EXERCISE, AND REST. 285 

All exercise of the muscles directly aids the circulation in 
the veins, and indirectly hastens it in the heart and arteries. 

657. When we walk , we breathe more rapidly than when 
sitting still. (§ 342, p. 150.) If we run, or labor with great 
violence, we breathe very rapidly. During the process of 
exercise, more fresh blood is carried in the arteries to the 
organs, especially the muscles, and the more impure blood 
is brought away in the veins. The changes of living and 
dead particles are more rapid. (§252, p. 115.) There is 
then a greater quantity of old and dead particles — more 
carbon and hydrogen — to be carried out of the system, and 
consequently a greater demand for oxygen to convert these 
into carbonic acid gas and water. For this purpose the 
chest expands, and we breathe more frequently, and give the 
lungs the increased quantity of air that is needed. Hence 
we see that exercise aids respiration, and is most advan¬ 
tageously taken in the fresh air abroad. 

658. When a boy is cold in the winter, he runs to get 
himself warm; when a passenger is insufficiently warm in 
his vehicle, he gets out and walks or runs by the side of his 
horse to warm himself. When a farmer sits in his house in 
a cold day, he has a large fire, sufficient to heat the room 
to near. 70°, in order to keep himself comfortable. If he 
ride at the same season, he wears a great coat, and wraps a 
buffalo robe about him. But, when he takes his axe and 
cuts his wood in the open air, he wants neithei fire nor 
great coat, perhaps not even his close coat. His exercise 
keeps him warm, and, if he labors violently in loading his 
sled or his wagon with heavy logs, he becomes uncomfortably 
hot, and may get into a free perspiration. The muscular 
action increases the amount of wasted atoms to be con¬ 
sumed in the body, and the more rapid respiration and 
circulation increase the fuel and oxygen for the internal 
fire, which burns more and more in proportion to the ac¬ 
tivity and violence of the labor. (§422, p. 181.) 


286 


PRACTICAL PHYSIOLOGY. 


CHAPTER X. 

Muscular Action strengthens the whole System, and aids the Brain 
and Mind. — Neglect of Exercise debilitates the whole Powers. — 
Various Persons need different Quantities of Exercise. — Too vio¬ 
lent Exercise exhausts. 

659. It will be easy now to understand how a muscle 
that is used grows and becomes hard and strong. The 
active contraction promotes the flow of blood and increases 
nutrition by the deposit of new particles of flesh. After the 
labor has ceased, there is less waste of particles by the absorp¬ 
tion of the old. But the rapid motion of the heart does not 
cease with the exercise; the increased flow of blood is thus 
continued, and with it the increased deposit of new particles 
in the muscles; and thus it gains in size and strength by 
labor. 

660. Thus we see that muscular action promotes diges¬ 
tion, respiration, circulation, and nutrition, and it assists the 
preparation and maintenance of animal heat. Finally, as the 
health and functions of the nervous system are connected 
with the condition of the other systems, we may safely add, 
that muscular exercise aids the brain also in its work, and 
that no mind can be the clearest and the most vigorous for 
study and reflection, unless the body is accustomed to action. 

661. A sagacious physician, whose domestic economy 
was worthy of all imitation, when any one of his daughters 
complained of a headache, was accustomed to inquire, first, 
whether she had taken her usual exercise abroad; and, 
if this had been insufficient for the purpose, he frequently 
advised, not medicine, but another walk. Some judicious 
schoolmasters, when they find their boys and girls heavy and 
indisposed to study, send them out to play awhile. After 
exercise out of doors, they return to their studies with new 
alacrity. If older students, when they find it difficult to fix 
their minds upon the subjects before them, — when the reason¬ 
ing powers are clouded and the imagination is dull, — would 


BONES, MUSCLES, EXERCISE, AND REST. 287 

leave their books and their studies, and walk, or otherwise 
use their muscles abroad, they might recover that energy of 
brain and mental clearness which they had struggled without 
success to gain while they were in their rooms. 

662. One of my friends, an unusually robust boy, went, a 
few years since, from the country to college. He was of a 
quiet, contemplative disposition, very fond of his books, and 
faithful to his plans of life. He did not enter into the 
active sports of the other students; and the walks in the 
neighborhood of the college did not interest him. Yet he 
was then in excellent health, had a good appetite, and ate 
heartily. Moreover, he was an industrious student, and a 
good scholar. While the first year wore away, he walked 
little, studied assiduously, and, at the end, his health was still 
good. The second year found him and left him about the 
same, except that he walked rather less. He was advised to 
pursue a different course, and the necessity of muscular 
action was urged upon him as a law of health. He ac¬ 
knowledged the law in general terms, but claimed to be an 
exception to its requirements. He had lived two years with 
very little exercise, and yet he was not only well, but was 
able to study as much as his fellows; he therefore supposed 
that he was exempted from the almost universal necessity of 
action abroad. His third and fourth years passed away, in 
much the same manner, except that he walked less and less, 
for the reason that it was more and more irksome to him; 
but his health was not very perceptibly deteriorated. After 
he left college, he taught school one year, and then com¬ 
menced the study of his profession, and pursued this about 
two years, with the same habit of physical inaction and 
mental industry. But in this period his appetite began to 
fail, and he suffered from indigestion. His powers of mind 
languished, and his spirits grew dull. He lost his power of 
application and habitual cheerfulness. At the end of this 
period he broke down, and was unable to pursue his pro¬ 
fessional studies any longer; he then gave them up, and 
went to his home a confirmed dyspeptic. There he re- 


2S8 


PRACTICAL PHYSIOLOGY. 


mained several years an invalid, incapable of any business, 
or of engaging in any more study. That firm and inflexible 
constitution, which had held out seven years against the vio¬ 
lation of the physical law, was equally inflexible with regard 
to recovery, and required more than seven years to be so far 
restored as to allow him again to engage in any pursuit. 

663. The same quantity of exercise is not necessary for 
the health of all men and women, nor are all able to endure 
the same amount of labor. It must be measured out accord¬ 
ing to the constitution, the strength, and the habits of various 
persons. What is necessary for one may exhaust another. 
The quantity of action should be determined, not by any 
previously established theory, but by its results in each case 
— by its effects upon each individual. 

664. If the exercise is too violent or too long continued, 
the body is rather exhausted than invigorated; the process 
of waste is carried on beyond the power of nutrition, and 
then the muscles grow thin and lank, rather than full and 
strong, and the individual sutlers from languor, and is ill 
fitted for any other labor. But if, on the other hand, after 
the exertion, we are only a little fatigued, but not languid, — 
if we are ready then for any other occupation, for reading, 
writing, or conversation, — we may be assured that the in¬ 
creased waste is counterbalanced by the increased nutrition, 
and the labor has strengthened rather than weakened the 
body. The exercise should never go beyond a slight fa¬ 
tigue, never to exhaustion, nor produce that uneasy rest¬ 
lessness which unfits one for any other immediate duty, and 
which rather wears unon than adds to the general health. 

665. Although tne muscles have a power of contraction, 
they have not a permanence of this power. The muscle 
needs alternate relaxation with its labor. One can strike with 
more force than he can pull, and lift a much heavier weight 
than he can continue to hold up, for even a few minutes. It is 
one of the severest and most painful punishments to compel a 
boy in school to hold out the arm in a horizontal position, 
even without a weight in his hand, for any length of time. 


BONES, MUSCLES, EXERCISE, AND REST. 2S9 


CHAPTER XI. 

Feeble Persons weakened by any Excess of Exercise, but strength¬ 
ened by very moderate Exertions. — Exercise must be adapted 
exactly to the Strength. — In this Manner Strength may be in¬ 
creased daily. — It is an Error for dyspeptic Students or Invalids 
of the City to attempt to be Farmers or Sailors. — Gymnasium not 
adapted to Powers of those who use it. 

666. We are told by some that they cannot walk or move 
in any way abroad, that it always gives them the headache or 
pain in the limbs, and that they return from their excursions 
sick and languid. This is, indeed, a truth; but it is very 
easily explained. These uncomfortable consequences flow, 
not from the mere exercise, but its excess. The walk which 
exhausted them may have been short compared with those 
which others take with ease, and return from with buoyant 
alacrity ; but it was too much for their feeble and unpractised 
limbs. But, although a mile exhausts, half a mile will prob¬ 
ably cause merely fatigue, and ultimately strengthen; and, if 
this be too much, a still shorter one will answer the desired 
purpose. 

667. If the exercise be judiciously begun, with just the 
quantity that is sufficient, and no more, it will leave the per¬ 
son in slight fatigue; but in a little while, he will feel more 
fresh and vigorous, and capable of making a still greater 
exertion. Adopting this method, the feeble must begin ac¬ 
cording to the degree of his strength, however small; and 
with proper management and perseverance, he may go on 
adding a little exertion day by day, and accomplish more 
and more. 

668. However small may be the person’s strength, that 
must be the measure of the exertion. However low the 
power, that must be the starting-point. Any other measure¬ 
ment, any other point of beginning, would be fatal to the 
hopes of gaining strength by the effort. 

A young man, in Waltham, Massachusetts, was very 


290 


PRACTICAL PHYSIOLOGY. 


feeble, but not sick. He was advised by his physician to set 
out upon a journey on foot, but was cautioned not to walk 
at any time until exhausted. He began his journey in the 
morning, and, with short exertions and frequent rest, he 
walked three miles on the first day, and was fatigued. The 
next morning, to his surprise, he felt more vigor and courage 
to go on, and started again. He walked on that day, in the 
same manner, and accomplished four miles before night. 
He thus gained strength and energy, day by day, adding little 
to little, and finally walked to Niagara Falls — more than 
five hundred miles. After viewing these to his satisfaction, 
he returned, in a much shorter time than he went. But he 
did not return by a direct course. He visited the interesting 
places in the neighborhood of his homeward route, and at 
the end of his sixth week, he reached home, having walked 
more than a thousand miles in forty-two days. On the last 
day he had walked forty miles, and was so little fatigued 
with the day’s journey, that in the evening he felt sufficient 
energy to visit his young friends in the neighborhood. 

669. There is a common notion, that, as great action 
gives strength to the strong, it will do the same for the 
weak; therefore the debilitated student and the languid child 
of the city, who have become so feeble as to be unable to 
carry on their studies or attend to their sedentary business 
in the counting-room, are advised to leave their occupations, 
and go into the country, and work with the farmers. They 
commence their labors with zealous courage; but they soon 
give up. They find that they are exhausted by the work, 
which the practised laborer accomplishes without apparent 
exertion or fatigue. Instead of being invigorated, they are 
weakened, and they abandon too frequently all hope of 
recruiting their wasted powers by muscular exercise. But 
if, instead of attempting to mow, plough, or dig, for several 
hours in succession, they undertake the lightest work, and 
do this for a few minutes or an hour or two, with fre¬ 
quent, and perhaps long intervals of rest, they gain power, 
m the pedestrian just now described. 


BONES, MUSCLES, EXERCISE AND REST. 291 

070. For the same purpose, and with the same mistake 
of means and ends, young men in ill health are sometimes 
sent to sea as sailors, and engage to do the work of the com¬ 
mon and practised seamen. They err in their estimate of 
the effect of hard labor on the weakened frame, and are 
obliged to give up their purpose or alter their plans. But 
a much better and more successful method is, to enlist 
as weak sailors, without wages, and without responsibility. 
This allows them to work only so much as their strength 
gains upon them; and, if this be judiciously expended, they 
will add to it daily, and accomplish all they desire, and 
return, after some months, in more vigorous health. 

671. It was supposed, twenty years ago, that the gym¬ 
nasium would furnish opportunities and inducements to ex¬ 
ercise for all such as were not required, by their business 
or their condition in life, to labor. In these establishments 
means were provided for using all the limbs and muscles. 
There were ropes to climb, parallel bars to walk upon with 
the hands, and wooden horses to mount upon or leap over. 
There were means for climbing, swinging upon the arms, 
leaping, vaulting, and for performing some of the feats of 
the rope-dancer, and some of the labors of the sailor. These 
exercises were active, and even laborious. Those who 
engaged in them made, or endeavored to make, the exer¬ 
tions which only strong men could make. But they were 
soon fatigued, and left the gymnasium; or, if they perse¬ 
vered, were nearly exhausted. The error was in not adapt¬ 
ing the mode to, and measuring the amount of exertion by, 
the strength of those who needed it. The students of Cam¬ 
bridge, in 1826, (§ 165, p. 78,) complained that they were 
fatigued, and sometimes overcome, rather than invigorated, 
at the gymnasium, and were unfit for study for some hours 
afterwards. The final result of this attempt to introduce 
this system of exercises into our colleges, schools, and 
cities, was a general failure. But, if they had been arranged 
and measured so as to correspond with the little strength of 
sedentary men, they might have still been in general use, 
and productive of great advantage to health. 


292 


PRACTICAL PHYSIOLOGY. 


CHAPTER XII. 

Kinds of Exercise. — Walking. — Sports of Childhood allowed to and 
beneficial to Boys. — Girls exercise more quietly, and with less 
Advantage. — English and American Women. — Exercise of the 
Arms and Chest. — Carpenters’ Tools. — Time for Exercise. — 
Morning and Evening not the best. 

672. There are as many varieties of exercise as there 
are muscles in the human body. It is not easy to determine 
which of these is the best, nor is it of consequence that we 
should settle the question in advance. There is no one 
kind that is better than all others, or can be substituted for 
all the rest. One kind uses one set of muscles, another uses 
another set. Walking employs the muscles of locomotion; 
cutting and sawing wood exercise the muscles of the arms 
and shoulders. Riding on horseback employs the muscles 
of the lower limbs, back, and arms, and agitates the whole 
frame. 

673. Walking is the most readily accomplished , and is 
within the reach of every one. There is every where a road 
or a field to walk in; and if this exercise be taken with due 
energy, as boys and young men usually take it, moving with 
alacrity, swinging the arms and calling into requisition the 
contractile power of most of the muscles of the body, it 
will ordinarily be sufficient for the maintenance of health. 
Walking is the most advantageous when it is bold and easy. 
The body should be carried erect, the chest allowed the 
greatest freedom of expansion. The arms should hang and 
swing freely from the shoulders. A stooping posture inter¬ 
feres with the action of the lungs; and a confinement of the 
hands, the folding the arms on the chest, or carrying them 
in a muff, limits the muscular exertion, makes the move¬ 
ments unnatural, and causes an ungraceful gait. 

674. The sports of boyhood, the games of the street and 
the playground, which not only require much muscular 
exertion but, are attended with exhilaration, answer all the 


BONES, MUSCLES, EXERCISE AND REST. 293 

purposes of health. By custom and the general opinion of 
society, boys are thus happily indulged. They are allowed 
and encouraged to run, jump, and leap, and even to shout. 
They are consequently in good health, and have great vigor 
of body and activity of motion. 

675. But the custom of society and the notions of pro¬ 
priety demand a different manner from the girls. They are 
not permitted to walk with that energy and vigor that their 
brothers are. There is a great fear of romping. They are 
required to be staid and quiet, and to confine themselves 
to walking. They are prohibited from the noisy plays, the 
bold activity of motion, and that free exercise of the lungs, 
which strengthen and delight the boys. And while the boys 
run and pursue any object of interest through the roads and 
fields, over rocks and hills, the girls are required to limit 
their movements to walking on the smooth and level paths 
which require comparatively little exertion. 

676. A walk of three miles is not frequent for American 
women; and, when a lady of a country town of New England 
walked sixteen miles at once, in the year 1842, it was con¬ 
sidered so extraordinary as to be made the subject of a news¬ 
paper article. But in England, a walk of some miles is an 
every-day occurrence for women; and thus they have means 
of locomotion ever at their command. When an American 
clergyman was visiting a family in England, it was proposed" 
by the young ladies to visit a friend who lived at the distance 
of five or six miles. He cheerfully consented, but was sur¬ 
prised that no carriage came to the door. They walked, 
and spent a part of a day with their friend. On returning, 
the ladies proposed to the clergyman that they take another 
way homeward, which would make a walk of three miles 
farther, and call on another friend. He consented, and they 
went this long, and, to him, wearisome way home. The 
females neither regarded the walk, nor even seemed to think 
they had done any thing extraordinary, or out of their usual 
habit; but the American gentleman was unusually fatigued. 

677. Some other employments give more exercise to the 
arms and upper part of the frame than walking. Garden* 

* 

/mfO 


294 


PRACTICAL PHYSIOLOGY. 


ing, raking, hoeing, and digging, call into play the muscles 
of the arms, shoulders, and back. Working with the car¬ 
penter’s and cabinet-maker’s tools has the same effect, and 
when either of these can be combined with walking, the 
best effects upon the health are obtained. 

678. Dancing, when practised at proper hours, and in 
sufficiently ventilated rooms, is an excellent exercise. It 
brings many muscles into action, and it is usually attended 
with cheerful exhilaration, that quickens the flow of blood 
and increases respiration. But the mere practising of atti¬ 
tudes, or the walking quietly through the figures, gives no 
exercise; and the late hours, crowded rooms, and night 
suppers, too often connected with this amusement, render 
it of very doubtful utility, if not certainly injurious. 

679. To the hardy and laborious, it may seem a matter 
of indifference whether we take exercise at one or another 
hour of the day; and, for those who work from morning 
till night, all hours are alike in this respect. Still, for the 
invalid, and for those who only exercise for a short period, 
and for the maintenance of health, all hours are not equally 
advantageous. It is common to recommend the morning as 
the time to walk. The freshness of the morning air has been 
the song of the poet, the theme of the moralist, the faith of 
the philosopher. All have conspired in its praise, and in 
urging upon the feeble and the sedentary the beauty and 
advantage of early action abroad. 

680. The morning may be the time for exercise of some, 
but it is not the best time for all. After the long fasting of 
the night, the body requires nourishment before it labors. 
(§ 113, p. 56.) It is apt to faint if it works before break¬ 
fast. Beside, the dews and dampness of the night, and the 
exhalations which have arisen from the earth, are upon the 
morning air, and must enter the lungs of those who are then 
abroad, and prevent their receiving the refreshing invigo- 
ration which a walk at another hour would give them. The 
same objection applies to evening and the night, and the 
sedentary should not then take their excursions in the 
open air. 


BONES, MUSCLES, EXERCISE AND REST. 295 

G81. The state of the digestive organs should be regarded 
when we exercise. We should not work just before eating, 
especially if we have long fasted and are hungry, for then 
the system is comparatively weak, and needs nourishment, 
and is therefore easily exhausted by exertion. And more¬ 
over, muscular action would expend the nervous energies 
that should be reserved to sustain the stomach in digesting 
the coming meal. (§ 164, p. 77.) Neither should we exercise 
immediately after eating, for the work of digestion requires 
all the energies of the system, until the food becomes thor¬ 
oughly mixed with the gastric juice. 


CHAPTER XIII. 

Place for Exercise. — Should not be in House, tut in open Air.— 
Exercise should be frequent and regular. — All need it, especially 
the Sedentary. — Consequences of Neglect. 

682. We need an abundant supply of oxygen to sustain 
the increased demand for nutrition and discharge of waste 
which is caused by muscular action. Exercise abroad in the 
open air gives more health and vigoi to both body and mind 
than exercise in the house. Some have prepared gymnastic 
apparatus in their garrets, or in their cellars, in order that 
they and their families may exercise without the trouble and 
exposure of going out of doors. Some gentlemen in cities 
saw and split wood in their cellars; but they fail of obtaining 
the full measure of good that action in open air would 
give them. Even those mechanics whose employments give 
them sufficiency of muscular exercise, especially those who 
work in close shops, would do well to add a walk abroad to 
their in-door labors; for they would gain in vigor of body, and 
freshness of spirit, and effective power, more than sufficient 
to compensate for the loss of time devoted to their renovation. 

683. Whatever may be the weather or the season, the 
demand of the system for exercise abroad is the same; for 



296 


PRACTICAL PHYSIOLOGY. 


we have the same wants, and need the invigorating effects of 
muscular action both winter and summer — in fair weather 
and in foul. Nor is there any sufficing objection to it, for 
very few days of the winter are so cold that we cannot keep 
ourselves comfortable by rapid walking, or other exertion; 
and, indeed, the colder the weather the more dense is the 
air, and the greater quantity of oxygen is received into the 
lungs to sustain the internal fire. (§ 444, p. 189.) Very few 
days are so stormy as to prevent this exercise abroad, and on 
such days it may be taken under cover of the house. 

684. This law for the health of the frame, and the neces¬ 
sity of exercise abroad, is one and the same for both male 
and female, for the rich and the poor. All can have a fuller 
development of strength, and health, and life, by taking it 
abroad; and all must suffer the same depreciation of life if 
they neglect it. There are none so favored in life as not to 
need it, none so high as not to be benefited by it, and 
very few so feeble as not to be able, in some degree or other, 
to obtain it. 

685. Exercise should be frequent and regular. The sys¬ 
tem wants this means of invigoration as regularly as it wants 
new supplies of food for nutrition. Every day, therefore, 
should have its own, and no day should have more. It is not 
enough for health that we live inactively for several tiays, then 
devote one day to action of the muscles. But many do so; 
they have, in all, a sufficiency of exercise, but they take it 
irregularly. A clergyman, within my observation, devoted 
Mondays to walking, or riding on horseback, and the rest of 
the week to mental labor. While writing his sermons, he often 
for three days scarcely left his room. He became dyspeptic. 
Some teachers labor incessantly in their vocation for weeks 
successively. They teach six hours daily in school, and read 
and study the other waking hours out of it, with the intention 
of devoting their vacation to excursions and labor, and then, 
they think, they shall get exercise enough for another term 
of confinement. 

686. The industrious seamstress, earning her scanty pit- 


BONES, MUSCLES, EXERCISE AND REST. 297 

tance by incessant toil; the shoemaker, working the whole 
day upon his bench; the mother, watching over her sick child; 
the faithful minister, writing for his people; and the judge, 
trying the issues of life and death — suffer as surely from in¬ 
door confinement, and want of daily exercise abroad, as the 
indolent, who have no occupation and no call for action. 
These must fall short of that full measure of power of body 
and of mind to do their present and pressing work, which a 
proper attention to the wants of the body would have given 
them. They may think they have no time for recreation 
abroad, and that an hour a day, spent in mere walking, is so 
much waste of opportunity of usefulness or of profit. But 
it is not so; the time required for the repair of the vital ma¬ 
chine is not lost, for the body will not work the most easily, 
and with its fullest energy and most successful effect, if it is 
not in the best order. None need this daily recreation more 
than those who are compelled to produce every day the 
greatest result from mental or physical in-door labor, and who 
want, for that purpose, the fullest vigor, both of their muscular 
and nervous systems, and the most complete control of their 
powers. 

637. The evil consequences of neglect of exercise are 
not sudden nor immediately perceptible. They are gradual 
and accumulative. They steal slowly upon, and secretly bind 
the strong man, and then take away his health. Dyspepsia, 
defective nutrition, muscular weakness, nervous irritability, 
and mental dulness, so manifest and oppressive as to compel 
the sufferer to change his pursuits or his habits, and betake 
himself to some means of relief, are remote results. But the 
immediate effects, however small and unnoticed, are none the 
less sure to come, and diminish the activity and force of life 
in proportion to the neglect. If this is continued, and vio¬ 
lation of this law is frequent, weakness necessarily follows, 
until marked and acknowledged disorder is established. 

688. It must be now considered as established that a cer¬ 
tain quantity of muscular exercise is necessary for the main¬ 
tenance of health, and for the best performance of the func- 


298 


PRACTICAL PHYSIOLOGY. 


tions of digestion, respiration, nutrition, and of the brain. 
The amount of this exercise may vary according to the con¬ 
stitution, and habit, and powers of the individual. It is best 
when so varied as to bring into play all the muscles of the 
body. It should be taken out of doors, and in the free air. 
This is necessary for all men and all women, of whatever 
occupation, and especially for those of no occupation. 


CHAPTER XIV. 

Amount of Exercise maybe greater than Health requires. — Body 
grows strong with judicious Labor. — Limit to Man’s Increase of 
Strength. — Fulness of Strength may be maintained to Old Age, 
with proper Care. — Man has a limited Power of Endurance.— 
No more Strength must be expended in the Day than is restored 
in the Night. — Men worn out by excessive Toil. — Length of 
Life differs with Amount of Labor. 

6S9. That amount of exercise which is necessary for 
health is not the limit of muscular power. If it were, we 
should be able to accomplish but a small part of the work 
which we now do, and the labors of the farm and workshop 
would not be effected. We have a power of muscular con¬ 
traction and of motion, which may be applied to the ordinary 
purposes of life. With this we cultivate the soil and carry 
on the operations of the mechanic arts, we navigate ships, 
and perform all our labor for pleasure or for profit. 

690.' It becomes a question to every man who works for 
profit, or who exercises more than is needed for the bare 
maintenance of health, how much can he work ? Have 
the moving animal frame, the muscles and the bones, an in¬ 
definite power of endurance and action ? It needs no physi¬ 
ological explanation to show that there is a limit to this 
power of labor. Then there comes another question — Where 
is that limit? How long can a man labor ? How much may 
he labor each day, and not wear upon his permanent health, 
nor interfere with his continuance of life? To a certain 



BONES, MUSCLES, EXERCISE AND REST. 299 

extent, the body grows strong with labor, and every exertion 
adds new particles and power to the muscular fibre. The 
man who walked to Niagara Falls (§ 668, p. 281) was stronger 
the second day than he was the first, and stronger the third 
than the second. He began with a power to walk three 
miles, and ended in six weeks with a power to walk forty 
miles. Whether he could have added still more to this 
power, or how much stronger he could have grown, is not 
known, for the experiment was not tried any further. In the 
same manner, any one unaccustomed to labor, if he has a 
good constitution and health, and if he proceeds gradually, 
and cautiously increases from small beginnings, can, in time, 
become sufficiently strong to do the ordinary agricultural 
labor. 

691. In this process of invigoration there may be fatigue, 
but there must be no languor nor exhaustion. But if either 
of these happens, — if the working man finds himself exhausted 
after his toil, if he is uneasy, and restless, and unable to sleep, 
and awakes the next morning unrefreshed and unprepared 
for new exertion, — he may be sure that he has overworked his 
frame, and reduced rather than increased his strength. 

But by faithful and prudent use of the power already 
gained, by never over-working on any one day, by always 
stopping short of exhaustion, additions are made to the 
strength day by day, for a certain period and to a definite 
extent. The laborer may increase his exertion as long as 
he feels this increase of power. But there must be, and is, 
a limit to this. No man grows infinitely strong, and sooner 
or later he must reach the end of his growth of power; then 
he possesses his fullest measure of strength. 

692. Having arrived at this fulness of strength, he can 
maintain it if he uses it discreetly and temperately, and if he 
exercises daily, but never expends in any one day more than 
its due portion of power. By this self-management, a man 
can keep himself in the highest working order, and he will 
be able to accomplish the most labor, not in any one day, nor 
in a single year merely, but in the whole course of life, and 


300 


PRACTICAL PHYSIOLOGY. 


protract that life and its full working power to the natural 
period. For this end, he must attend to the first sensation 
of weariness, and never permit it to increase to exhaustion ; 
and, whenever he begins to feel this, he may understand that 
the waste of life has reached the measure of the nutrition; 
and, if he then stops and rests, this last will go on, and he will 
in due time be refreshed and ready again for labor. In this 
way, he will always work at the full flow of his strength, and 
be able to perform the greatest amount of labor. 

693. There is a common and mistaken notion, that man 
has an indefinite power of endurance, and may work until 
fatigue or exhaustion compels him to stop; and that whatever 
strength is not used in the hour and in the day, and is car¬ 
ried to the bed at night, is so much lost. Therefore some 
weak men labor as long as their strength holds out, and some 
strong men labor as long as the day will permit them. In 
consequence of this daily fatigue and exhaustion, they are 
never in full vigor, they are always reduced somewhat below 
their natural standard, and commence each day with a lower 
energy, and work upon a lower tide of power, than they 
otherwise might have done. 

694. By this excess of labor, a man expends more strength 
in the day than he recovers in the night, and rises unrefreshed 
in the morning. He is wasting his constitution, and, if he per¬ 
severes, he reduces himself to a lower standard, and then he 
is compelled to limit his exertions and perform lighter labors. 
In this reduced and weakened condition, he may, by proper 
management of his diminished strength, lead a life of con¬ 
siderable action, and perhaps regain his original vigor. Or 
he may, by still overworking, reduce himself below the 
power of labor, and, becoming decrepit, suffer the pains and 
debilities of old age long before his time. 

695. Those overworked and exhausted men, completely 
broken down and unable to labor, are not very common, yet 
they may be found. A farmer, within my observation, began 
his life with small means, but with great energy and large 
hope. He seemed to think there could be no end to his 


BONES, MUSCLES, EXERCISE AND REST. 301 

power and labor. He rose with the sun in summer, and let 
it go down upon his toil. He allowed himself a few hours 
for sleep, and a few minutes for food, and no time for di¬ 
gestion. But in a few years he was worn out, and was then 
and afterwards, in health and strength, an old man. For the 
rest of his years he was an invalid, and unable to undertake 
even the lightest labor of his farm. Such instances of com¬ 
plete waste of power by excess of labor may be rare, yet the 
lesser degree of exhaustion is very prevalent. We find many 
who, after the middle period of life, feel obliged to favor 
themselves, and do lighter work, and with more frequent in¬ 
tervals of rest than others, because they have overworked and 
expended their power; and there are not many laborious 
men who do not thus begin to slacken in their labors soon 
after, perhaps before, they have passed their fiftieth year. 

696. This constant labor, not only wastes the strength, but 
breaks up the constitution, and finally disarms it of its power 
of resistance to the causes of death. Hence the life of the 
overwrought laborer is, in general, shorter than that of the 
moderate worker. According to the registration of deaths in 
Massachusetts, for the 8 years and 8 months ending with 
1849, it seems that the average length of life is the shortest 
with those classes of men whose days are spent in the severest 
toils. The ages and professions of men are recorded in these 
registers; and from these we learn that 6340 farmers died at 
the average age of 64 years and 10 days; 2715 common day 
laborers, at the average age of 46 years and months ; and 
1452 sailors, at the average age of 43 years and 4 % months. 

697. The farmer is not obliged to make so continued 
and unremittingly severe exertions as the day laborer. He 
has a cap’tal in store, and, in most cases, can have help at 
command, and suspend his own labor, or take the lighter 
tasks. But for the laborer, each day’s bread must be ob¬ 
tained by that day’s toil. To him there is allowed no rest 
nor choice of work; and to him is usually assigned the 
heaviest and the hardest. The sailor is presumed to be, in 
all cases, a man of full strength. He must assume his share 

26 


302 


PRACTICAL PHYSIOLOGY. 


of the ship’s labor, and perform a stout man’s duty. He 
must take his turn, and watch night as well as day. Pie can 
never expect to have an entire night’s rest. 

Making all due allowance for the difference of habits of 
many in these several classes, — admitting that the poor la¬ 
borer is often an invalid, and is worse clothed and fed than 
the farmer, and that more accidents happen to both the laborer 
and the sailor than to the farmer, and even other circum¬ 
stances that interfere with the full enjoyment of health, — still 
much of this great difference of longevity — one fourteenth 
longer life of the day laborer than the sailor, and a quarter 
longer for the farmer than for the laborer—must be charged 
to that excess of toil, which wears out the man prematurely. 


CHAPTER XV. 

Languor always succeeds great Efforts.— Serious Injury may follow. 

— Growing Children need various and light Exercises. — Youths 

cannot endure the full Labor of mature Men. 

698. The period of vigor and of a man’s productive 
power is shortened, the sum of the whole life’s exertion is 
materially diminished, and its last stages rendered compara¬ 
tively useless, by attempting to work beyond the power of 
permanent endurance. This is the result of long-continued 
over-exertion. But even if it is not long continued, if it is 
merely temporary, the same result of languor, and lessened 
ability for labor, follows for a proportionably short period 
An extraordinary labor of one day is followed by extraor¬ 
dinary languor the next; and whether this greater exertion, 
this excess of waste of the powers over the nutrition, be more 
or less, it must be followed by a proportionate feebleness. 

699. Excessive temporary exertions are followed, not cnly 



BONES, MUSCLES, EXERCISE AND REST. 303 

by a corresponding languor, but sometimes by serious injury 
to the constitution. We are sometimes told by men that, 
since they strained themselves by lifting, or running, or by 
violent working at a fire, or some other occasion, they have 
not enjoyed their former health, nor have been able to work 
with their former energy. These evil consequences more 
frequently follow the excessive efforts of boys and young 
men. Dr. Hope says, that violent corporeal efforts, of every 
description, accelerate the circulation, and cause an unnatural 
pressure of blood upon the heart. “ In growing youths, ex¬ 
cessive rowing is one of the most efficient causes of this 
disturbance of the heart. Violent gymnastics produce the 
same effect.”* 

700. The natural exercises of children, their sports and 
games, which they enter upon and go through with boisterous 
zeal, give them light, and varied, and sufficient muscular 
action. None of the muscles are tasked too much, none 
called to labor for any length of time. Children and youth 
are not made. for hard labor; whatever work is required of 
them should be light, varied, and short. Great exertion 
during the forming and growing period would very soon ex¬ 
haust their strength, and, if continued, it would prevent the 
full development and growth of the muscular system, and 
even wear down the constitution. 

701. A man does not reach his full measure of strength 
and power of endurance until he has passed his 25th year. 
And if, under that age, he is exposed to the hard labor and 
privations which older men seem to endure with impunity, 
and in situations where can be no relaxation nor favor shown, 
the health and strength of the youth fail; and, if there is 
danger from the labor and exposure, the youth is the first to 
die. Young soldiers sink under the labors and privations of 
the camp sooner than mature men. Napoleon complained 
that boys were sent to supply his army, rather than men who 
could endure the toils and the sufferings of the campaign. 


Diseases of the Heart, Part III. Chap. 1, 


304 


PRACTICAL PHYSIOLOGY. 


The development of strength is progressive through the 
several periods of early life , and each period has its appro¬ 
priate means and opportunities. The plays of childhood 
prepare the muscles for the light employments of youth ; 
these increase the muscular energies, and prepare them for 
the full power of labor in manhood. Each is necessary, and 
none can be omitted, nor can they be interchanged. Some 
children are exclusively devoted to study, and have no incli¬ 
nation to active play. They prefer their books, while other 
children are playing abroad. These develop their nervous 
systems, but their muscular powers are dormant. They 
become good scholars, but are weak in body, and ultimately 
their mental energies sometimes falter. 


CHAPTER XVI. 

Labor requires healthy Organs of Digestion and Nutrition. — Good 
Food, sound Lungs, and fresh Air. — Healthy Skin, sound Con¬ 
dition, and Cooperation of the Brain and Nervous System. — Exer¬ 
cise most beneficial when the Brain is lively and Spirits cheerful. 

702. Muscular action presupposes waste, (§ 252, p. 115,) 
which is supplied immediately from the blood, and remotely 
from the food. The active have, comparatively, new flesh, 
and the inactive old flesh. (§ 257, p. 117.) In order to sup¬ 
ply this waste, and make new muscular atoms, the organs 
that effect the changes in the food, and the channels through 
which it passes in its progress from its condition as food in 
the mouth to its new condition as flesh in the textures, should 
be in good health. A working person must, therefore, have a 
sound stomach and good digestion. The organs of circulation 
and nutrition must also be in good order; for otherwise the 
food cannot be converted into blood, nor the blood into flesh, 
to meet the changes that the action of the muscles demands. 

703. Next in importance to a sound condition of the 
organs of digestion and nutrition is the supply of good food. 
Food alone is the source of all our bodily strength; and it 



PRACTICAL PHYSIOLOGY. 


' 305 


gives this power only in proportion as it can be converted 
into new atoms of flesh. The laboring man wants rich and 
nutritious food to sustain him in his exertions. He cannot 
work with his fullest energy with poor and innutritious ali¬ 
ment. Just in proportion as his diet is low or lacks in nutri¬ 
ment, must his strength and his power of labor fail. The 
English trainers, who develop the greatest muscular force, 
eat, or give their men the best of bread and the best of meats, 
— beefsteak and mutton. On the same principle, the judi¬ 
cious but economical farmer feeds his cattle, and gives the 
oxen that work better hay than those that lie still. 

704. Tlic laborer not only wants nutritious food , but that 
which can be converted into flesh with the least cost of 
power. Digestible food requires but little exertion of the 
stomach to convert it into chyle; but heavy bread, tough 
meats, matters that are badly cooked, and all other sorts of 
food that are hard to be digested, are not converted into 
chyle without much labor. If more strength, or more nervous 
power, is expended in digestion, of course less can be ex¬ 
pended upon the muscles of motion. This is well understood 
when one has eaten a very heavy dinner, which absorbs all 
the energies of the system for its digestion. Then he can no 
more work with his hands than he can when he is using his 
feet with all his force. The same is true, though in a lesser 
degree, when any food that is of difficult digestion is taken. 
While this is going on, the man may work, but his power of 
labor is reduced in proportion to the difficulty of the digestive 
operation. A person, therefore, can accomplish the most 
when he has eaten light bread and the best pieces of meat; 
and the laboring man, whose life is in his power of labor, 
can afford to eat no other. 

705. The waste caused by exercise must find free outlet 
through the skin and the lungs. Both these organs must, 
then, be in a healthy condition in the laborer. His surface 
must, by frequent bathing, be kept free from every thing which 
would clog its pores, or obstruct its operations. The in¬ 
creased waste through the lungs demands a greater supply 

26 * 


306 BONES, MUSCLES, EXERCISE AND REST. 

of oxygen, and, consequently, a more frequent respiration 
during exercise. But if the lungs are unsound, or inflamed, 
or in any way impaired, or if their motions are impeded by 
any external incasement around the chest, they cannot re¬ 
ceive air sufficient to carry off* the excess of wasted particles 
which are thrown into them. For this cause, a man laboring 
under asthma or consumption cannot run, or pump at a fire- 
engine, or mow grass, or perform any labor that requires 
great and continuous effort. An abundant supply of pure air 
is equally necessary to carry off* the excess of waste. Men 
who work in close shops, mines, and the holds of ships, have 
less power than those who work in the fields. 

706. The heart, being the engine that propels the blood, 
is required to work with greater force and rapidity when 
exercise demands a greater supply of nutriment in the tex¬ 
tures. If this organ is unsound, it cannot make this extra¬ 
ordinary exertion ; and those who have diseased hearts cannot 
perform very active labor. Mr. H., a very industrious farmer, 
once complained to me “ that he could not cut his wood, 
nor mow his grass, as he had done, for the exertion imme¬ 
diately caused great distress about the region of the heart, 
and then he could not move.” He was suffering from a dis¬ 
ease of the heart, of which he afterwards died. 

707. The brain is connected with all the muscles through 
the medium of nerves, and directs and sustains their motions. 
The state and health of the brain and mind affect, very ma¬ 
terially, the value of exercise and the power of labor. We 
will, or determine, to move the finger; at the same instant 
the volition is sent from the brain to the muscle that moves 
the finger; this then contracts, and the finger moves. This 
is the case with all voluntary motion ; yet the volition of the 
mind and the action of the brain are not always observed. 
Some motions are performed so much from habit, that we are 
unconscious of the volition. When we walk, we contract the 
muscles, those which bend the joint of the hip, the knee, and 
ankle, of one side; and, at the same moment, we contract the 
muscles which straighten these joints on the other side. At 


PRACTICAL PHYSIOLOGY. 


307 


the next moment, we reverse this action, and contract the 
straightening muscles of the first side and the bending mus¬ 
cles of the opposite side; by these motions on opposite sides, 
the limbs are lifted and carried one before the other, alter¬ 
nately, and the body moves onward. 

708. While we walk easily over a smooth and familiar 
path, we may direct the energies of the brain partially, but 
not exclusively, to other matters, and talk or think of agree¬ 
able and interesting subjects. But if the walk becomes diffi¬ 
cult, — if the mind is required to pick the way through wet or 
stony places, or perform any severe labor, — all the energy 
of the brain is required to direct and sustain the muscles of 
motion, and then conversation and thought are suspended. 
But if, on the contrary, the brain is all absorbed with other 
subjects, — if we are engaged in deep thought or oppressive 
anxiety, — the muscular contraction is not so easily effected 
and controlled, the strength of the muscles is not so well 
sustained, the exertion wears more upon the body, and con¬ 
sequently exercise under such circumstances is not so in¬ 
vigorating, and labor not so effectual and profitable. 

709. Although the brain and mind must not be absorbed 
or oppressed with care or thought when we exercise or labor, 
yet they should not be dormant. They should be lively and 
engaged. The exercise should have an object. Walks 
through pleasant scenes and among interesting objects, ex¬ 
cursions in pursuit of flowers, minerals, or other natural ob¬ 
jects, do more for the health than those which have no object. 


CHAPTER XVII. 

Labor should have an adequate Object. — Hope and Confidence give, 
and Doubt and Fear diminish, Strength. — Cheerfulness and Mel¬ 
ancholy have similarly opposite Effects. — Effect of Passion, Al¬ 
cohol, on Strength. 

710. Labor for profit, as well as exercise for health , 
should have an adequate object. The mind must be satis- 



3C8 BONES, MUSCLES, EXERCISE AND REST. 

fied, or else the brain will not cooperate with its full energy, 
and give the muscles full power. When the farmer fears 
that the cultivation of his fields will produce no crop, when 
the laborer believes the wages are inadequate to his services, 
and the mechanic thinks his wares will return him no profit, 
they cannot make their greatest exertions, or, if they do, it is 
at a cost of the permanent power. But the laborer who is 
well paid generally feels a motive that stimulates the brain, 
and strengthens the muscles, and enables him to work vigor¬ 
ously and successfully. 

711. Hope and confidence give almost unmeasured strength ; 
but despair weakens, almost paralyzes. When a man 
falls overboard at sea, he swims for his life as long as 
he has hope of rescue or can move his limbs, until, fatigued 
with his labor, and in despair of obtaining relief, he seems 
unable to swim any farther, and suspends all exertion, and 
gives himself up to death. But if, at this moment, a boat 
comes in sight, or land appears to him, a new hope is ex¬ 
cited, new strength is given, and he swims again with a 
power which was impossible a few minutes before. 

712. The same effect of confidence that strengthens the 
muscular system, and of doubt that weakens and sometimes 
paralyzes exertion, may be seen in any of the labors of com¬ 
mon life. If the student walks grudgingly, with doubt as to 
the efficacy of the exercise, and fear that he is misappropri¬ 
ating his time; if the over-cautious girl walks with fear lest 
the exercise flush her cheek too much, or the perspiration 
soil her garments, or the exercise derange her dress; if she 
moves with timid anxiety lest she assume ungraceful atti¬ 
tudes, or in any way transcend the becoming delicacy of a 
lady, — the brain will not cooperate earnestly with the work, 
nor send full stimulus to the muscles; the limbs then labor 
languidly, and the exercise fails to invigorate the system. 

713. Cheerfulness and melancholy have the same op¬ 
posing effects on muscular power as hope and despair. 
Whatever depresses the spirits, depresses the energies of the 
brain, and consequently the energies of the locomotive ap* 


PRACTICAL PHYSIOLOGY. 


309 


paratus. Thf> slow and measured step of the funeral proces¬ 
sion, and the light, elastic step in the merry dance, are both 
equally indicative of the energies of the muscles. There is 
as certain a difference between the power of muscular con¬ 
traction in the dancer and in the mourner, as there is between 
the buoyant spirit of the one and the oppressed spirit of the 
other. In one, the heart is joyous, the brain is active, and 
the motion quick and easy; while in the other, the heart is 
sad, the brain is heavy, and the movements are slow and 
wearisome. 

714. All alcoholic liquors stimulate the muscular ener¬ 
gies temporarily . A man under the influence of these can 
make greater exertions, and for a short time accomplish more 
work. But this increased power, like the effect of passion, 
is of very short duration. While stimulated by excitement, 
a man may strike heavier and quicker blows; but then the 
unnatural labors soon weary and exhaust him. All his ex¬ 
cessive exertions make a draft upon his permanent constitu¬ 
tional power, and leave him weaker than they find him; and 
iie who habituates himself to depend upon the stimulus of 
spirit to give him strength for labor, like all others that 
overwork, wears himself out early, and brings on the infirmi¬ 
ties of age before the natural time. 


CHAPTER XVIII. 

Attitudes. — Spine supported by Muscles equally on both Sides. — 
Spine very strong. — Porters. — Pedlers carry Burdens on Head, 
and Spine erect. — Centre of Gravity over Line of Support. — Head 
so carried. — This Attitude easiest and most graceful. 

715. The attitudes assumed in exercise or labor are of great 
importance. The structure of the spine, and the arrangement 
of the muscles which support it, give this column its greatest 
strength and flexibility when it is held erect. The spine 
curves from back to front, and from front to back ; yet these 
curves are so balanced that the upper end of the column, the 



310 


PRACTICAL PHYSIOLOGY. 


resting-place for the head in its natural position, is vertically 
over the base at the pelvis. 

716. The spine, as well as the other bones, is held in its 
erect position by a double series of muscles, (Fig. LVII.,) 

Fig. LVII. Internal Muscles of the Back. 


a, b, Spinous processes of the 
back-bone. 

c, Longissinus dorsi, longest 
muscle of the back. 

d, Muscle extending from the 
pelvis to the ribs. 

e, Muscles extending from the 
vertebrae of the loins to those of 
the back. 

f g, Muscles extending from 
the vertebrae of the back to those 
of the neck. 

h, Muscle extending from the 
back and neck to the head. 


which are placed on both sides of the back-bone, where they 
form a cushion of flesh, and are easily felt. The lowermost 
of these are fixed by one end to the hips, and by the other to 
some of the bones of the back; others are attached to one and 
then another of these little bones ; and others still are attached 
to the ribs and to the back-bone. All these serve to bend the 
back to one or the other side, and forward or backward. 












BONES, MUSCLES, EXERCISE, AND REST. 311 

The uppermost bend the head. They serve also to keep the 
head and the back in their erect position. 

717. The muscles on the opposite sides of the spine are 
naturally of the same size and length, and equally strong. 
They give to each side of the back the same support, so long 
as they are accustomed to the same amount of exertion. 
But if we allow the back to bend to one side, the muscles 
within the curve will be shortened, and those on the outside 
will be lengthened. The muscular action is then increased 
on the convex, and diminished on the concave side; for the 
muscles on the outside of the arch are obliged to exert a 
constant and much greater force to prevent the further curv¬ 
ing of the spine than was necessary merely to keep it bal¬ 
anced in the erect position; while very little action is 
required of those which are on the opposite side and within 
the curve. 

718. The structure of the back-hone gives it great strength 
as well as flexibility . Being composed of alternate bones and 
cartilage, and held together by strong ligaments and supported 
by many muscles, it is capable of bearing great burdens. 
All the upper parts of the body, more than half of its weight, 
and all the burdens that we carry on the head, the shoulders, 
the back, and the arms, rest upon it. Porters who are long 
trained to their business will carry upon their shoulders, or 
upon their heads, a burden of some hundreds of pounds. The 
Turkish porters in Smyrna, Asia Minor, carry enormous loads 
on their backs. A friend who has been there writes to me, 
“ The porters in Smyrna have a pack on their backs, about 
twenty inches wide, flat on the outside, so that the load lies 
on it steady without fastening. 1 saw one take a box of Ha¬ 
vana sugar on his back, to carry from the boat up to the 
warehouse, a short distance from the water. The sugar 
weighed four hundred and fifty pounds, or more. Captain N. 
of the navy said to him, 1 You had better add a bag of coffee,’ 
which weighed one hundred and thirty pounds. The porter 
said, ‘ Put it on,’ which he did. He, the porter, then turned 


312 


PRACTICAL PHYSIOLOGY. 


to Captain N. and said, 4 If you will give me a dollar, I will 
carry you on the top of these.’ ” 

719. I once saw, in the streets of Louisville, Kentucky, a 
colored woman carrying a tub of water upon her head, and a 
pail of water in each hand. There it was not unfrequent to 
meet a woman with a large pail of water on her head, which 
she carried with apparent ease and without spilling. We 
often meet the Italian pedlers carrying a large tray covered 
with images, or flower-pots, or toys, upon the head. They 
carry this with as much apparent security as others would 
carry them in their arms. Those who bear upon their heads 
heavy burdens which require strength, or pails of water that 
must not be spilled, or fragile merchandise that must not 
be broken, carry their heads very erect and their back-bones 
very straight. They hold the upper extremity of the spine 
directly over the lower end. 

720. This perfectly erect position of the spine affords the 
easiest method of carrying, not only burdens, but the head 
and the trunk, in the ordinary walks of life. Any one can 
try the experiment of holding a pole erect in his hand by one 
end. If it be vertically erect, he will exert no more strength 
than barely to lift the weight. But if it be inclined to either 
side, it will require considerable exertion to prevent its fall¬ 
ing. So, if the head be bowed forward, if the chest be bent 
downward, then the weight is not immediately above the point 
of support; it does not rest upon this foundation, but it must 
be held up by the exertion of the muscles, which is a very 
wearisome labor. 

721. In order to carry the head and body with the greatest 
ease, we must be governed by the same law as in carrying 
any burdens. We must bring the weight, the centre of its 
gravity, perpendicularly above the point of support. But, 
if we have any weight added to one side of the body, we 
must change the direction of the spine, so that it shall bring 
the centre of weight in the proper line. This we do instinc¬ 
tively. When a boy carries on his breast an armful of wood, 
he leans backward to bring the weight over the base of the 



BONES, MUSCLES, EXERCISE, AND REST. 


313 


spine. The fat man with large abdomen does the same, and 
for the same reason. Otherwise they would necessarily exert 
great force of the muscles of the back, to prevent their fall¬ 
ing forwards. 

722. If a porter stands perfectly erect when he carries a 
trunk on his back, (Fig. LVIII.,) the line of gravitation falls 
behind his natural line of support, and tends to throw him 
backwards. To prevent this, and bring the burden over 
the point of support, he leans forward, (Fig. LIX.) 

Fig. LVIII. Fig. LIX. 




For the same reason, the hod-carrier leans to the left 
when he carries his burden on his right shoulder, and to 
the right when he bears it on the left shoulder. When 
a boy carries a heavy pail of water with one hand, he leans 
as far as he can to the opposite side; but, as he does not lean 
far enough to bring the centre of gravity over the point of 
support without spilling the water, he throws out the other 
arm, and carries it in a horizontal position, to create a greater 
weight on that side, and balance the weight of water. And 
often he finds it easier to divide his water into two pails, and, 

27 







3L4 


PRACTICAL PHYSIOLOGY. 


by carrying one in each hand, brings the centre of weight 
over the point of support, with his spine perfectly erect. 

723. Upon the same principle of carrying the centre of 
gravity over the centre of support, every one should carry his 
head erect and his back-bone straight. It is not necessary 
for this to obliterate the natural curves of the spine, but 
to carry its line of support vertical from its base to the top. 
This will bring the head directly over the lower end of 
the spine. In this attitude, the weight of the head, trunk, 
and whatever burdens are borne, resting upon the bones, 
very little muscular action is required; and the bones of the 
lower limbs, and the general course of the spine, are in the 
same line. When these bones are in this upright direction, 
and the upper balanced upon the lower, it requires but little 
muscular exertion to hold them in their places. But if the 
lower bones are turned, or the spine is bent to either side, 
it requires a constant exertion of the muscles on the convex 
side of the joint or the spine to prevent it from bending 
farther. Whatever muscular strength is expended in main¬ 
taining the attitude, cannot be devoted to any other purpose. 

724. Tkis attitude is not only the easiest > but the most 
graceful. Stooping the body, or bending the head forward, 
when walking or standing, interferes with the elegant flexi¬ 
bility of the spine, and is awkward and uncomfortable to the 
person. Among those who carry burdens upon their heads 
we find the most frequent instances of graceful attitude and 
gait. Captain Ball, in his “ Seven Years in Spain,” says, 
“ It is wonderful to see the amazing burdens that the Spanish 
women carry on their heads, and walk at so rapid and safe a 
pace without the least accident. It is remarkable that the 
female peasantry in Spain have a more graceful and comely 
style of walking than the ladies, which I have repeatedly 
heard accounted for by the burdens that they carry on their 
heads requiring a certain degree of steadiness to balance.” 


BONES, MUSCLES, EXERCISE, AND REST. 315 


CHAPTER XIX. 

Erect Attitude best for Walking. — For Labor. — For Mechanics and 
Farmers. — For great Exertions. — For Speakers. — Spine curves 
from Front to Back. — Becomes bent by much stooping. — Position 
of Students and Writers raises the Shoulders and curves the Spine 
from Side to Side. — Curved Spine frequent among Girls, but not 
among Boys. — Injures Spinal Cord. 

725. “ In walking , it is all-important that the body be held 
as upright as possible , the shoulders being kept back, and 
the breast projected somewhat forward, so as to give the 
chest its full dimensions. The lungs being, by this means, 
allowed sufficient room to expand fully, breathing is rendered 
free and easy, and every vital action is performed with vigor. 
The attitude thus assumed in walking, places all the organs 
of the body in their most natural position, and frees them 
from all constraint.” * 

726. The wielding of the heavy sledge of the blacksmith, 
and planing of the hard wood of the wheelwright, are done 
with comparative ease if the body is kept erect. Such op¬ 
erations of agriculture as hoeing, mowing, ploughing, are 
generally easiest in the same position. Two men mowed 
side by side during a summer. One of these men was rath¬ 
er tall, large, and very muscular, and was reputed the 
strongest man in his town. The other was rather under the 
common height, of slender form, but very active. When 
mowing, the strongest bent his body down, and struck his 
scythe with all his might. The other stood erect, and, with¬ 
out much apparent effort, swung his scythe as one swings a 
cane. These two men, making such different efforts, per¬ 
formed equal work in the course of the day. But when they 
went home at night, the strong man was wearied and almost 
exhausted; the other was somewhat fatigued, but lively and 
elastic. 

* Journal of Health, Vol. I. p. 120. 


316 


PRACTICAL PHYSIOLOGY. 


727. This erect position is particularly attended to by 
those who wish to exert the most effective force, and to strike 
the heaviest blows. Soldiers, who endure fatiguing marches 
and fight with the greatest energy, are especially directed to 
maintain the erect attitude. So the prize-fighters are taught 
to stand in the struggle; their back is straight, their shoul¬ 
ders thrown back, and breast forward; then their arms are 
completely under their control. The best public speak¬ 
ers and readers stand in the same position. Their chests 
are free to expand, and they inhale large portions of air.; the 
head is erect, and the windpipe is not compressed; then the 
air can be thrown forcibly from the lungs, the voice is full, 
and the articulation easy and effective. 

728. The healthy spine, in its natural position, curves 
from front to back and from back to front, but not from side 
to side. When left to itself, it assumes this shape; yet its 
structure of alternate bones and cartilages allows the column 
a great variety of motions and positions; but the elasticity of 
the cartilages tends to restore it to its natural direction, after 
having been bent to either side. So that, after leaning and 
bending the spine to the left or to the right, by force of the 
muscles, when these cease to act, the side of the cartilages 
which was flattened springs upward, and throws the spine 
again into its natural position. But if the column be turned 
to one side frequently, and continued for a long period, and at 
the same time be pressed down by a weight, the compressed 
side of the rubber, having no opportunity to regain its usual 
form, will become permanently thinner, and the opposite side 
thicker; and then the whole pile would, without any external 
aid, remain curved. 

729. This great flexibility of the spinal column allows it 
to bend in any direction , and, for a short period , without 
danger of permanent curvature , if afterwards the upright pos¬ 
ture be assumed and maintained. But, if we continue these 
positions for a long time, the spine does not easily recover its 
proper shape. If the student bends his back and leans his 
head down, to bring the eyes nearer his book, if the seam- 


BONES, MUSCLES, EXERCISE, AND REST. 


317 


stress bends her chest forward over her sewing, or if the en¬ 
graver or watchmaker has his bench so low that the spine 
must be curved forward to bring himself near to his work, 
and if they sit in this manner for months and years, the car¬ 
tilages are compressed beyond the power of reaction. The; 
front part is flattened and the back part is thickened ; it 
becomes wedge-shaped, and consequently the back-bone is 
permanently crooked, and the person stoops or is round- 
shouldered. 

730. The same law applies to the lateral line of the back¬ 
bone, and similar habits of compression of the cartilages 
bring on curvatures from side to side. The position assumed 
at school while writing, (Fig. LX.) and often while studying, 
throws the spine out of its straight, lateral line, and bends it 
to one side or the other. The table or desk for writing or 


Fig. LX. 


Fig. LXI. 



drawing is usually higher than the elbow, as it hangs from 
the shoulders of the pupil sitting on the seat. In order, then, 
to write or draw, the right arm and elbow are raised and rested 
upon the elevated table. This raises the right shoulder, and, 
in raising it, bends the upper part of the spine over from 
the right to the left, and depresses the left shoulder. Then, 



318 


PRACTICAL PHYSIOLOGY. 


in order that the head should still be over the base or point 
of support, the upper curvature is balanced by an opposite 
lower curvature. While the upper part of the spine is curved 
to the left, the lower part, at the loins, is curved to the right, 
and the whole column assumes somewhat the shape of the 
letter S in its lateral direction. At the same time, the lowest 
and the highest portions are nearly straight, and the head is 
vertically above the base of the column. (Fig. LX.) 

731. The same effect follows from a position sometimes 
assumed in reading. The table is higher than the suspended 
elbow, and the reader does not sit directly facing it, but 
rather obliquely, and, lolling sidewise, raises the elbow upon 
the table, and rests the head upon the hand. This raises the 
shoulder, bends the spine, and produces the same result that 
comes from the unnatural posture in writing and drawing. 
If these positions are frequently changed, if one shoulder is 
raised as often as the other, and neither elevation is continued 
for a long time, no curvature of the spine will follow. But 
if either bent position be assumed frequently, and maintained 
for a long time, the cartilages will lose their elasticity, and 
become compressed on one side and expanded on the other. 
In the natural form, the shoulders are of the same size; they 
both rest upon the back of the chest, and lie upon the ribs, 
which are fixed upon the spine. If we examine any active 
boy, or any playful, healthy girl, we shall see that the shoulders 
are exactly alike; they are of the same height, and have the 
same shape. But, if we examine many girls who are pursu¬ 
ing or have finished their education, we shall find that one 
of the shoulders is grown out, and is higher, and projects 
farther forward than the other. 

732. The habits of school children, and especially of girls, 
of students, clerks, draughtsmen, and of some others, create 
a fearful frequency of this spinal distortion. Dr. Warren 
says, “ In the course of my observation, I have been able to 
satisfy myself that about half the young females, brought up 
as they are at present, (1845,) undergo some veritable and 
obvious change of structure; and, of the remainder, a large 


BONES, MUSCLES, EXERCISE, AND REST. 319 

number are the subjects of great and permanent deviations; 
while not a few entirely lose their health from the manner in 
which they are reared.” And again, “ I feel warranted in the 
assertion, already intimated, that of the well-educated females 
within my sphere of experience, about one half are affected 
with some degree of distortion of the spine.”* Dr. Warren 
substantiates his opinion by that of Lachaise, a French author 
upon the spine, who, in speaking of the lateral curvature, 
says, “ It is so common, that, out of twenty young girls who 
have attained the age of fifteen, there are not two who do not 
present very manifest traces of it.” A fashionable mantua- 
maker, of extensive experience and observation, informs me 
that she is obliged to stuff with cotton a large proportion of 
the ladies’ dresses, on one side or the other, to make them 
exactly symmetrical. 

733. Nature has given to all — to both female and male 
— sufficiency of bone and muscle to sustain them in the most 
graceful and healthy position; and when these are faithfully 
used, and their strength developed, they fulfil their purposes, 
and keep the form straight. The lateral curvature of the 
spine is very rarely found among boys. Their various and 
free exercise strengthens all their muscles, and prevents it. 
But it is very common among females, who exercise less, and 
wear external supports, which are intended to take the place 
of their natural framework and muscular power, and sustain 
the body. But these substitutes not only fail of their pur¬ 
pose, but sometimes bring on the very deformity they were 
intended to prevent. Although nature has provided all the 
proper supports for the spine, yet, when they are not used, 
they become weak, and then the spine bends to one side. 
This lateral deformity is rarely found among laborious farm¬ 
ers or mechanics employed in the heavy trades, or among 
porters, or even hod-carriers, who carry heavy burdens on 
their shoulders or heads, but in sedentary persons, who lift 
the least, and whose work is the lightest, the muscles of 
* Preservation of Health, p. 13. 


320 


PRACTICAL PHYSIOLOGY. 


whose backs have no other employment than to hold the 
spine erect. 

734. The curvature of the spine not only injures the sym¬ 
metry of the frame and lessens its height, but it distorts the 
chest and diminishes its capacity , and interferes with the free 
motions of the ribs. Accordingly, the lungs have less space 
for rest and less room for expansion, and therefore can re¬ 
ceive less air at each inspiration; then, imperfect purification 
of the blood, and, lastly, a deficient nutrition of the body, 
must necessarily follow. Sometimes serious diseases of the 
lungs are brought on by this curvature of the spine, and 
Dr. Hope says, “ The majority of hump-backed persons are 
ultimately attacked by disease of the heart.” 

735. The rings in the vertebrae (Fig. XXXIV.) being placed 
one upon another, form a channel or tube through the whole 
spinal column. This channel is of the utmost importance in 
the animal structure, for it encloses the great nerve called 
the spinal marrow , that extends from the brain to the trunk 
and the lower part of the system, and supplies all these parts 
with the principle of life. This great nerve begins in the 
brain, and reaches to the end of the spinal column. In the 
course of its descent, it sends out on each side nerves to the 
heart and lungs, to the organs of digestion and of motion. 
All the parts, therefore, of the trunk and all the extremities 
depend, more or less, upon the healthy condition of this great 
nerve for their fulness of life and freedom and energy of 
action. 

736. Any change in the shape of the spinal column, or in 
the relations of these bones to each other, must diminish the 
capacity of this canal, and, of course, press somewhat upon 
its great nerve. This pressure upon this nerve interrupts its 
freedom of action, and interferes with the communication 
between the brain and the parts of the body which receive 
nerves through this channel. This must be the natural con¬ 
sequence of all distortions of the spine, all permanent curva¬ 
tures from side to side, and of all unnatural curvatures from 
front to back, or from back to front. 


BONES, MUSCLES, EXERCISE, AND REST. 321 


CHAPTER XX. 

Day is Time for Labor. — Experiments. — Soldiers. —Miller. — Sleep. 

— Quantity of Sleep. — Night proper Time for Sleep. — Deficient 

Sleep causes Weakness. — Circulation feeble, and Heat less in 

Sleep. — Difficult Digestion disturbs Sleep. 

737. The day is the time for labor, and the night is the 
time for rest. This seems to be the almost universal law of 
nature. During the light of day, the air is more pure, and 
respiration is better sustained, the changes of particles are 
more easy, and consequently the muscles are better strength¬ 
ened. The light of the sun has, in some way or other, a 
great influence upon the energies of the body and the mind. 
The effect of a long series of cloudy days upon the spirits 
is familiar to all; we then become dull and querulous about 
the weather, and the return of the sunshine is received 
with a burst of joy, as if it brought back new life. Miners, 
who spend most of their daytime within the earth, become 
bleached and dull. Mechanics and shopmen, who work or 
transact business in imperfectly-lighted shops, have a lower 
degree of energy and health. 

738. Night labor is attended with the double disadvantage 
of bad air and darkness. The evil consequences of this were 
shown in the experiment of two French regiments. “ One 
of them, although it was in the heat of summer, marched in 
the day and rested at night, and arrived at the end of a march 
of 600 miles without the loss of either men or horses; but 
the other, who thought it would be less fatiguing to march 
in the cool of the evening, and part of the night, than in the 
heat of the day, at the end of the same march had lost most 
of the horses and some of the men.” * 

739. A similar experiment is partially tried by individuals, 
almost every where, with the same success. Milkmen and 

* Art of Living Long and Comfortable, p. 172. 


322 


PRACTICAL PHYSIOLOGY. 


market-men in the neighborhood of cities, and workmen in 
tide-mills, spend a part of the night in their business, and 
make up their loss of sleep in the day; but in a few years they 
are very glad to discontinue this course, and confine themselves 
to daylight labor. Mr. G. owned and worked a tide-mill, which 
could run only for a few hours succeeding a full tide, which 
came as often in the night as in the day. In course of a few 
years, this frequent night work wore so much upon him as to 
compel him to exchange his tide-water power for steam 
power, which he could use to suit his own convenience. 
Having given up night work, and limited his labor to the 
day, from a feeble he has become a robust man, and is able 
to accomplish more in the new than in the old system. 

740. It is a law of nature that all animals shall suspend 
their actions, and sleep. The alternations of day and night 
harmonize with this want of the living animal body, and 
afford seasons of activity and of rest. Man needs to follow 
this natural indication, and alternate his sleep and wakeful¬ 
ness daily. Sleep is nature’s restorer of exhausted power, 
and, though we retire wearied, we awake refreshed and 
strong; the expended energies are recovered, the strength 
brought back, and we are again ready for action. In the 
state of sleep, all motion of the voluntary muscles is stayed, 
and the brain suspends its active functions; but the invol¬ 
untary functions go on as when awake; the chest moves, 
the lungs breathe, and the blood is purified, the heart beats, 
the blood circulates, and the system is nourished. 

741. The quantity of sleep that is necessary is varied by 
so many circumstances, that no rule can be established for 
all. The time of life and the peculiarities of constitution 
make a difference. The sluggish and the lymphatic need 
more sleep than the active and the nervous. Some sleep very 
much, and are not refreshed, nor ready for action, if they 
are deprived of their usual quantity of rest. Others take 
very little sleep, and cannot obtain more. Without giving 
any precise rule, it is sufficient to say that men and women 
who have arrived at adult years, and developed their full 


BONES, MUSCLES, EXERCISE AND REST. 323 

strength, need from seven to nine hours’ sleep. The habits 
of sleeping create a difference of necessity, for a time at 
least, and cannot easily and suddenly be broken. 

742. The sleep in the day does not compensate for the 
loss of the night sleep. The soldiers who rested in the day, 
and marched at night, had as much sleep as the others, who 
slept at night; and yet they suffered much more from sick¬ 
ness and exhaustion. (§ 738, p. 321 ) The most perfect sleep 
and refreshing rest is obtained in the stillness of darkness, 
when all nature reposes; and it is all in vain that any one 
struggles against this law of his being. He may sleep in the 
day, and labor or watch in the night, but his waking hours 
are then not so bright, nor is his energy of life so great, as 
otherwise it would be. 

743. There are few who do not, now and then, devote a 
night, or a part of a night, to some labor, to travel, to parties of 
pleasure, or to watching with the sick. None of these escape 
the penalties that always follow the violation of the law of 
rest. Whatever may be the time required by habit, or the 
constitution, for sleeping, for the recovering of exhausted 
power, that time cannot be shortened without impairing, in 
some measure, the strength and activity of the next day. 
With less than the required quantity of sleep, the body is not 
completely refreshed, nor has it the full energy for action. 
If each day is expected to accomplish its entire work, each 
night must have its complete rest; and whatever is taken 
from the sleep must be taken from the power of labor. If 
any one cannot retire at his accustomed hour, and still wishes 
to have his usual power of action on the next day, he must 
protract his rest in the morning as much as it was shortened 
at night. 

744. During sleep, the circulation is more feeble, the res¬ 
piration is slower, and the heat is generated less rapidly than 
in waking hours, (§ 436, p. 187,) and, consequently, we are 
less able to resist the effects of cold; and if they exposed to 
a current of air, we are more liable to suffer than when we 
are awake. We therefore sleep under more clothing in the 


324 


PRACTICAL PHYSIOLOGY. 


night than we wear about the business of the day. If pos¬ 
sible, one should not go to bed cold, for it is difficult, when 
sleeping, to recover the heat that has been lost. 

745. Sleep is the most refreshing when taken in large and 
airy chambers. These rooms should, therefore, be ventilated 
daily, and at all seasons, by opening the windows, or other¬ 
wise. The lodging-rooms should never be used for any other 
purpose — for sitting, working, cooking, or eating. The bed 
and bedding should be opened and thoroughly aired every 
day. A very hard bed affords but few points of support for 
the body, which is, therefore, not so well rested while lying 
upon it. A very soft, downy bed allows the body to sink 
within it, and keeps up too great a heat, and debilitates rather 
than strengthens the sleeper. 

746. Nutrition goes on during sleep. But the food should 
be digested before retiring to rest. (§ 121, p. 59.) Sleep is 
disturbed with unpleasant dreams after a late or indigestible 
supper. The stomach works with difficulty, and the man 
dreams of being in difficult situations, or of attempting pur¬ 
poses which he cannot accomplish; still greater oppression 
at the stomach produces distressing dreams and nightmare; 
and in neither case is the natural and complete refreshment 
obtained from the sleep. 


BRAIN AND NERVOUS SYSTEM. 


325 


PART VII. 

BRAIN AND NERVOUS SYSTEM. 

CHAPTER I 

Nervous System.— Coverings of Brain.— Spinal Cord.— Nerves of 
Sensation and Motion.—Distribution. 

747. The nervous system consists of the brain, the spinal 
ctrd , and the nerves. The brain is in the head : its size and 
shape correspond to the size and shape of the skull. Its ex¬ 
ternal surface is not smooth and level, but it is broken into 


Fig. LXII. Brain. External Surface. 



a, Right lobe. b, Left lobe. c, c, Division of the lobes. 

various parts called convolutions , giving the organ the appear¬ 
ance of a collection of small lobes, with depressions between 
them, (Fig. LXII.) The substance of the brain is soft and 
28 




326 


PRACTICAL PHYSIOLOGY. 


somewhat pulpy; it is of very delicate texture, and can be 
easily separated by the fingers. The outer portion is of a 
pink color, and is called the cortical part. The inner portion 
is of a gray or ashy color, and called the cineritious part. 

It is supposed, by some, that these two parts of the brain 
have different offices; that one is the organ of the mental 
operations and the affections; that, through it, the mind acts 
and the feelings operate, while the other is supposed to be 
the organ of sensibility, and, upon that, impressions from the 
sensory nerves are received, and in it sensations are created 
and perception takes place, and that it holds the commu¬ 
nication with all the rest of the body. But how far this sup¬ 
position is true is not shown, nor is it necessary for us to know. 

748. The brain is covered and held together by three mem¬ 
branes. The inner and the middle of these membranes are 
very delicate, and give the brain a soft cushion to lie between 
it and its bony enclosure. The outer membrane is thick and 
very strong, and would hold the brain in its position and 
retain its shape even when removed from the skull. These 
membranes surround the brain on all its sides, above and 
below. The inner and soft membranes dip into the brain 
between the convolutions or little lobes, and separate them 
superficially. 

The brain is divided into two parts , called the right and 
left lobes , (Fig. LXII. «, b } ) which are exactly alike on the 
two sides. These are separated by a partition wall or a wing 
(Fig. LXII. c, c ) of the same membranes that cover the organ. 
This partition runs from the front to the back of the skull, 
and almost to the bottom of the brain. It supports the two 
lobes in their position, and prevents them from pressing upon 
each other when we lie down. 

749. The brain is also divided into two other parts — the 
greater or cerebrum , and the lesser or cerebellum . The greater 
occupies almost the whole of the cavity of the head above 
and in front. The lesser is behind and below, just above the 
neck. A wing of the membranes extends across the skull 
from side to side behind, and separates these two parts of the 


BRAIN AND NERVOUS SYSTEM. 


327 


brain. This wing is attached to the bone, and gives support 
to the brain, and protects it from the injury that might com6 
from jars; and it also prevents the upper and larger organ 
from pressing upon the smaller organ below. 


Fig. LXIII. 
Brain and Cord . 


750. The spinal cord extends from the 
brain through the whole length of the 
back-bone , (Fig. LXIII. b .) In the bottom 
of the skull there is a large hole, which 
is placed directly over, and opens into, 
the channel in the spine. This channel 
is formed by the rings of the successive 
vertebrae. It is closed on all its sides, 
and gives a sufficient and secure place 
for this great nerve or extension of the 
brain. This spinal cord is composed of 
pulpy, nervous matter, like that of the 
brain, and is protected by the same deli¬ 
cate and strong membranes that cover 
the organ above. 

751. The brain sends nerves to the 
whole body. There are holes in the base 
of the skull through which twelve pairs 
pass outward. These are alike on the 
two sides. The optic nerves pass for¬ 
ward to the eyes. The auditory nerves 
pass sidewise to the ears. The others 
pass through other holes to the face, and 
to some other parts of the body. Twelve 
pairs go directly from the brain, (Fig. 

LXIII. «,) and thirty pairs go from the 
spinal cord, (Fig. LXIII. e, e, e.) These 
nerves divide and multiply until their 

branches reach every part of the body, 

7 , j i i j spinal nerves, 

and every organ, muscle, and blood-ves- ^ 

sel is connected with the brain by its appropriate nerve. The 

nerve of the face passes out from the skull below the ear, 

(Fig. LXIV. «,) and sends its branches and filaments over the 



a, Brain. 

b, Spinal cord. 

c, c, c, c, Roots of 





328 


PRACTICAL PHYSIOLOGY. 


whole face. Other nerves are in like manner spread over the 
neck, (Fig. LXIV. e,) the arm, and every part of the body. 


Fig. LXIV. Nerves of the Face and Neck. 



a, b, Nerve of the face. d } Nerve of the forehead. 

752. Two kinds of nerves extend from the hrain and spinal 
cord to the body —those of sense and sensibility, called sen¬ 
sory nerves ; and those of motion, called motory nerves. The 
sensory nerves receive the external impressions, and convey 
them to the brain. This class includes both the nerves of 
special sense, as the optic, auditory, gustatory, and olfactory 
nerves, which go to the eye, ear, tongue, and nose, and also 
the nerves of general sensibility, by which we feel pleasure 
and pain, heat and cold. The motory nerves convey from 
the brain to the muscular texture the stimulus of motion. 
The muscles are supplied with both classes of nerves, and, 
therefore, have both the feeling and motory power. 

753. These two kinds of nerves — the motory and sensory — 


BRAIN AND NERVOUS SYSTEM. 


329 


perform separate offices; each effects its own purpose, and no 
more; and each one neither interferes with, nor can take the 
place of, the other. If, from any cause, the nerve of motion 
alone is disordered, separated, or pressed, the muscles cannot 
move, but the power of feeling remains. But if the other 
nerve—that of sensibility—is injured, there is no feeling, but 


Fig. LXV. 

Section of the Spinal Cord, 
a 


a power of motion. If the motory nerve that connects the 
brain with the muscles of the jaw and lips is divided in any 
animal, he may still smell his food with his nostrils, and feel it 
with his lips, but he cannot open his mouth to take it in and 
masticate it. But if the sensory nerve is divided, the animal 
cannot feel the food with his lips, although he can move them 
to take it in. 

754. These nerves have separate roots in the spinal cord; 
the sensory nerve arises in the 
posterior, (Fig. LXV. 
and the motory nerve in the an¬ 
terior part. (e,e } e,e.) These 
nerves are united (c, c, c, c,) 
soon after they leave the spine, 
and are for some distance in¬ 
cluded in the same sheath, yet 
their branches are not equally 
distributed to all the parts of 
the system. The skin has no 
power of motion, but it has 
great sensibility. It is, there¬ 
fore, very largely supplied with 
sensory nerves, but not with 
motory nerves. On the other 
hand, the muscles, being exclusively organs of motion, are 
very largely endowed with motory nerves, but with a limited 
supply of the sensory fibres. In consequence of this, when 
the surgeon amputates a limb, great pain is suffered while the 
knife is cutting through the skin, and comparatively little 
when the muscles are divided. 

28 * 



a , b. Section of the cord. 

c, c, c, c. Spinal nerves. 

d , d , d , d. Posterior or sensory 
roots of the spinal nerves. 

e , e, e, e. Anterior or motory roots 
of the spinal nerves. 












330 


PRACTICAL PHYSIOLOGY. 


CHAPTER II. 

Sensation is in Brain. — Produced by Impressions on outer Ends of 
Nerves, and carried on Nerve to Brain. — No Sensibility nor Power 
of Motion in Part which does riot communicate with Brain. — 
Cutting Nerve, or Pressure on Nerve, paralyzes Parts to which it is 
distributed. — Foot asleep. — Injury of Spinal Cord paralyzes Parts 
below. 

755. Sensory nerves carry impressions from their outer 
extremities, in the organs of sense, and in the flesh, to their 
ends in the brain, where the sensation is excited. The trunk 
of the healthy nerve has no feeling, and receives no impres¬ 
sions ; it is merely a messenger to carry the impressions from 
the points where they are made, to the brain, where they are 
recognized. Sensation is not in the outer end of tlie nerve, 
nor in its trunk, but in the brain, at the inner end of the 
nerve. There are, then, three things in this work of sensa¬ 
tion : 1st, the extremity of the nerve, which first receives the 
impression; 2d, the brain, which perceives the impression; 
and, 3d, the connecting line of nerve between them; and 
if either of these be wanting, or injured, there can be no 
healthy sensation. The power of motion requires the same 
three things — the brain, through which the mind determines 
or wills the motion; the nerve, to carry this volition or di¬ 
rection to the muscle; and the nervous termination, which 
imparts the stimulus to the moving texture. 

756. The poicer of motion , and the sensibility of any part , 
require this constant and uninterrupted nervous communica¬ 
tion with the brain; and if, from any cause, this connection be 
suspended,— if any nerve be cut, or divided, or pressed, — the 
power both of motion and of feeling is destroyed, or im¬ 
paired, in the part where the nerve terminates. The familiar 
circumstance of the foot being asleep is caused by the pres¬ 
sure upon the nerves that lead down the leg to this extremity. 
The communication between the terminations of the nerves 
below and the brain above is thus interrupted, and then the 


BRAIN AND NERVOUS SYSTEM. 


331 


foot can neither feel nor move. In this state we try in vain 
to walk, for the muscles cannot act; and if we strike the 
foot, we feel no pain; but when the pressure is removed, and 
the communication restored, sensibility returns to the foot, 
and the power of contraction to the muscles. 

757. Most of the nerves of sensation and of motion do not 
pass directly from the brain to the trunk and the extremities, but 
from the spinal cord. (Fig LXV. e , e , e, e.) The upper part of the 
cord sends nerves to the arms, and to the chest and its organs, 
the heart and the lungs. The middle part supplies the ab¬ 
domen, and the lower part supplies the lower limbs. These 
several organs and parts of the body hold their communica¬ 
tion with, and receive their nervous life from, the brain, 
through this nerve, or rather bundle of nerves, in the back¬ 
bone, and the branches which pass from it. 

758. There are thirty pairs of nerves, or branches, which 
go from this cord to the body and the limbs. These parts 
must not only have free nervous connection with the spinal 
cord, but, through the cord, they must have uninterrupted 
communication with the brain. If this communication be 
interrupted or broken off in the cord, all the parts of the 
body which are supplied with nerves from it, below the point 
of obstruction, will be deprived of their power of sensation 
and motion. This palsy of the muscles or parts of the body, 
and interruption of the regular operations of the organs, 
happen occasionally from such accidents to the spine as pro¬ 
duce pressure upon its great nerve, and sometimes from dis¬ 
tortion, or curvature, which, in a lesser degree, produce the 
same effect upon the cord. 

759. Mr. J. fell, in the year 1830, and struck the hollow 
of his back on some stones, and injured the spine about the 
middle of the back. The cord was injured or pressed at that 
point, and free communication between the lower parts of the 
cord and the brain interrupted. All the parts of the body 
below the injury were palsied. But the power of motion and 
of sensation was restored as the cord recovered from the 
effects of the accident, and the pressure was removed, or the 


332 


PRACTICAL PHYSIOLOGY. 


injury healed. In another case, the paralysis was more ex¬ 
tensive, having been produced by an injury at the lower part 
of the neck. There was, at first, a total loss of voluntary 
power over the lower extremities, trunk, and hands, slight 
remaining voluntary power in the wrists, rather more in the 
elbows, and still more in the shoulders. The muscles of the 
ribs were also paralyzed, and the breathing was carried on 
entirely by means of the diaphragm.* If the injury, in the 
last case, had been higher in the neck, above the origin of 
the nerve which leads to the diaphragm, this muscle also 
would have been paralyzed, and death would instantly have 
taken place, for want of power of respiration. 

760. The higher any injury occurs to the spinal cord, the 
more extensive must be the bad consequences; that is, the 
nearer the root the interruption happens, the greater num¬ 
ber of its branches must be affected. An injury, or a curva¬ 
ture, may cause pressure upon the whole or a part of this 
nerve, or upon a part of its branches only, and thus interrupt 
or interfere with the communication between the brain and 
the organs to which these branches lead. In this way the 
lungs and the stomach are sometimes disturbed or enfeebled, 
and difficulty of breathing or dyspepsia produced. 

761. At first, Mr. J. (§ 759, p. 329) suffered great pain 
and palsy of the lower limbs. But the injury was not per¬ 
manent; the pressure on the cord was gradually and slowly 
removed, the pain was relieved in all the parts, and the power 
of motion returned to the muscles successively; and, finally, 
he regained the use of all his muscles, except those which 
lift his feet. These are still palsied and useless to him; so 
that now, though it is seventeen years since the accident, 
and he moves his thighs and legs, and can press his feet 
downward, yet he cannot bend them upward on the ankle ; 
and when he walks, the foot hangs down, and the toes strike 
the ground first instead of the heel. Probably a fibre or 
branch of the motory nerve, that leads to the muscles which 
bend the ankle, was injured beyond recovery. 


Carpenter’s Physiology, $ 178. 


BRAIN AND NERVOUS SYS1EM. 


333 


762. It is not to be presumed that the pressure upon the 
spinal marrow, from a curvature or distortion of the spine, 
will produce so sudden or perceptible injury as Mr. J. suf¬ 
fered ; but his case illustrates the connection between the con¬ 
dition of the spinal marrow and the health and power of the 
organs and systems which derive their nerves from it. These 
cases (§ 759, p. 329) show also how the organs may suffer 
from an injury to the spine, or interruption of the action of 
the great nerve which connects them with the brain. What¬ 
ever may be the cause of this injury, the consequence of im¬ 
paired life and diminished power must follow, in those parts 
or organs which receive their nerves from the spinal cord 
below the point of pressure. 


CHAPTER III. 

If Nerve is injured or diseased in its Trunk, Pain is felt at its outer 
Terminations. — Injury of Optic Nerve excites Sensation of Light.— 
Arrangement of the Brain and Nerves like that of Bells and Servant 
in Hotel. 

763. The impression being made on the outer extremity of 
the sensory nerve, and the sensation being in the brain at the 
other end, the nerve is a mere channel, or highway, through 
which the impression is carried inward. The healthy nerve 
receives no impressions and originates no sensations in any 
part of its course; it only carries those which it receives at 
its end; and the brain recognizes and understands no other 
power or function in the nerve than that of receiving im¬ 
pressions at its outer extremity. It therefore refers all feel¬ 
ings and impressions, which come to it through the nerve, to 
those extremities. 

764. If, by accident or disease, any impression is made 
upon the trunk of the nerve, — if we touch or irritate it, in any 
part of its course between the outer and inner ends, — this im¬ 
pression is conveyed to the brain, but that organ refers it, 
not to the point where the impression is actually received, 



334 


PRACTICAL PHYSIOLOGY. 


but to the end of the nerve, where impressions should be 
received; and there, at the extremity, the irritation or sensa¬ 
tion seems to be. If there is injury of the nerve, the pain is 
not felt at the wounded place, but at the minute extremities. 
Thus, when we strike the elbow against a table, and hurt the 
trunk of the nerve that leads to the fingers, we do not feel pain 
at the elbow, which was struck, but a tingling pain at the fin¬ 
gers, where the terminations of this nerve are distributed. 

765. Likewise, the pain of any local disease of the nerve 
is felt at its extremities. The excessively painful nervous af¬ 
fection of tic douloureux is felt on the surface of the cheek; 
but the cause is not, as is supposed by those unacquainted 
with the cause, in the skin or flesh, but in the trunk of the 
nerve leading from the face to the brain. This cause may 
be situated any where in the course of the nerve, between 
its outer ends in the flesh and the inner end in the brain. 
Wherever it may be, the effect is the same, and the painful 
sensations seem to be at the terminations of its branches 
which go off from the nerve below the diseased point. 

766. The disease may be in a nerve very near the brain, 
and yet the pain is felt at its remote extremity. Miss W. 
complained of very severe and sharp pains in the arm and 
hand. It seemed to her, she said, as if thousands of needles 
were incessantly running through the flesh. For this, all 
sorts of applications had been made to the seat of the pain, 
and all without effect. Suspecting the pain had a remote 
origin, her physician examined the back-bone at the place 
where the nerve went from the spinal cord to the arm, and 
there discovered great tenderness — pressure on this spot in¬ 
creased the pain in the arm and hand. Blood was then taken 
from the back at this point, and the remote distress in the 
arm and hand was immediately relieved. She afterward had 
similar pains, at different times, in the side, the stomach, the 
lower extremities, and the feet, and these were relieved by 
cupping, or by the application of leeches, or a blister, over 
that part of the back-bone where the nerve of these several 
suffering parts originated. 


BRAIN AND NERVOUS SYSTEM. 


335 


767. The nerves of special sense are subject to the same 
law as the sensory nerves; they receive natural impressions 
at their extremities, but not in their course. They can con¬ 
vey to the brain, not common feeling of pleasure or pain, but 
such impressions as are made on their outer terminations, 
which are expanded in the several organs of sense. The 
optic nerve conveys the impression of light, the auditory con¬ 
veys sound, the gustatory conveys taste, and the olfactory 
nerve conveys the impression of odors. When these nerves 
are irritated, or touched, or diseased, they still excite similar 
sensations. If we close the eye and press the ball upon the 
optic nerve, an impression is made upon the brain similar to 
that caused by light. If we strike suddenly upon the eye, or 
even the temple, so as to jar this nerve, the brain sees flashes 
of light. Dr. Howe has often tried these experiments with 
the blind, — both with those who were born in this condition, 
and had never seen light, and with those who became blind 
after birth, — and they all saw flashes and stars. 

768. When we receive a blow on the side of the head, so 
as to jar the auditory nerve, or when the ear is diseased, we 
hear a ringing in the ear. In some states of disease, men 
complain of bad taste on the tongue. In vain they wash and 
purify the mouth — still the offensive taste remains; for it is 
not an impression made upon the tongue and carried thence 
to the brain, but the impression of some disturbance or 
derangement of the trunk of the nerve excites a disagreeable 
sensation in the brain, which refers.it back, not to the spot 
which is disturbed, but to the termination in the tongue. 

769. Whatever excites any nerve in its course will pro¬ 
duce an effect upon the brain similar to that which is pro¬ 
duced by impressions made upon its terminations, and the 
sensations will be referred back to the ends of the nerve as 
their seats. An electric shock, if passed through the nerve 
of the ear, will give the sensation of sound; and if through 
the nerve of the eye, the sensation of light. If we apply a 
piece of zinc and copper to the upper and lower surface of 
the tongue, and let their edges touch each other, they excite 
a sense of unpleasant taste. 


326 


PRACTICAL PHYSIOLOGY. 


770. This arrangement of the brain and nerves and their 
terminations, or points of impression, with their relation to 
each other, is similar to that of the bells in a hotel and the 
servant who watches them. The wires extend from the 
several rooms to the corresponding bells in the central room, 
or the servants’ hall. Whenever the occupant of any room, as 
No. 66, wants any thing, he pulls his wire, and the bell No. 
66 rings. The servant, seeing this, immediately recognizes 
a want in No. 66, and refers this to no other room. His 
only conception is that of the connection of bell No. 66 with * 
room No. 66. Now, if any one should hit the wire between 
these two points, and ring the bell, the servant would have the 
same conception of a want in No. 66. Possibly this room 
might be cut off, and the wire and bell remain; if then the 
M/ire is drawn and the bell rings, the conception is still the 
same of a want in No. 66. So the brain, when it receives 
any impression at the inner end of the nerve of the finger 
or the eye, has no other sensation than of something pleasant 
or painful in the finger, or of light in the eye; and even 
though the finger or the eye be lost, if the nerve remains and 
is irritated, the brain still has the same sensation. 


CHAPTER IV. 

Pains in amputated Limb. — Motion excited by touching Motory 
Nerves. — Rapidity of Nervous Action. — Voluntary and Involun¬ 
tary Organs. — Involuntary Motions fatigue less than Voluntary. 

771. Tiie last section will explain some singular facts in 
regard to amputated limbs. Even after the nerves are di¬ 
vided, or cut off, the remaining parts, if irritated, may excite 
in the brain the same sensations as if they were entire. 
Sometimes men, after a leg has been amputated, complain 
of suffering great pain in the feet and the toes of the sepa¬ 
rated and buried limb; and some, believing there was a 
mysterious connection between the body and the lost limb, 
have caused it to be taken up and examined, to see if there 



BRAIN AND NERVOUS SYSTEM. 


337 


were any cause of suffering pressing upon it, while others 
have laughed at the fallacious imagination. A gentleman, 
whose arm was recently amputated by one of my friends, for 
a cancer in the hand, told me that, when the end of the nerve 
was touched in the stump, he felt his old pain in the hand. 
In these and similar cases, there was no mistake in the sensa¬ 
tion ; the remaining trunk of the nerve, being pressed or 
irritated, carried this impression to the brain, which referred 
the pain to the separated limb, and to no other. This has 
sometimes happened many years after amputation. The 
reasoning faculty corrects the error, yet the sensation remains. 

772. The same law holds in regard to the nerves of mo¬ 
tion. The muscles yield obedience to the mandates which 
they receive from the brain. When the mind wills to move 
the finger, the brain sends the volition and the stimulus of 
contraction along the motory nerves to the muscles on the 
fore-arm, and they contract and bend the finger. But the 
muscles yield to every stimulus they receive through the 
motory nerve. If, therefore, we prick or irritate one of the 
nerves of motion, the muscles to which it leads will contract; 
if we apply a galvanic shock to it, it will produce the same 
effect; and even the limbs of the dead body, for a short 
time after death, can be made to move by the powerful appli¬ 
cation of galvanism to the nerve of motion. 

773. False sensations are produced directly in the brain , 
independent of the nerve, by some disease which disturbs, 
or excites, or impresses the brain, at the points where the 
nerves terminate. When this impression is received in the 
brain, from the outer end of the nerve, a true sensation is 
excited; but when it is made directly upon the brain, by dis¬ 
ease or disturbance, without the intervention of the nerve, a 
false sensation is the consequence. 

The communicating-bells in the hotel (§ 770, p. 336) may 
be rung by any jar, or any thing moving them, independent 
of the wires that should pull them; then the servant would 
have the usual idea of some one ringing at the farther end 
of the wire, and something wanting in the chamber where 
29 


338 


PRACTICAL PHYSIOLOGY. 


the wire ends. Whether the bell be rung by some one in 
the chamber, or by some one touching the wire in its course, 
or by any jar acting on the bell itself, the same thought is 
produced in the mind of the servant whose business it is to 
watch them. In like manner, whether the impression be first 
received at the outer termination of the nerve in the organs 
of sense, or in the flesh, or on its trunk, or at its inner ter¬ 
mination in the brain, the same sensation is excited of sound 
in the ear, sight in the eye, or feeling in the flesh. 

774. These false sensations are created in some diseases. 
The insane sometimes have false hearing and vision. They 
seem to hear the sounds of voices, and even articulated lan¬ 
guage. When the imagination is highly stimulated, one sees 
visions. The timid see frightful apparitions, which seem to 
assume as distinct a form and color as the real objects of day. 
Sometimes false vision and false hearing exist together in the 
same person. He not only sees the form of the object, but 
he hears the sound of the voice. Men, when suffering from 
delirium tremens , are troubled with these false sensations. 
They are often frightened by the voices of spirits or the sight 
of enemies. The error in these cases is not in the eye, nor 
in the ear, but in the brain itself. The disease which disturbs 
this organ produces the same sensations in it that would be 
produced if the impressions were first made on the eye or ear, 
and then conveyed by the nerve to the brain. 

775. Communication is very rapid through the nerves — 
so rapid as often to seem to be instantaneous. If we tread 
upon a thorn, or a heated iron, the sensory nerve conveys the 
impression to the brain; this organ recognizes the impression, 
and then directs that the muscles of the limb lift the foot out 
of danger, and sends this mandate through the nerve of mo¬ 
tion. These two processes — the passage of the painful im¬ 
pression from the foot to the brain, and of the volition from 
the brain to the muscle of the foot — seem to be simultane¬ 
ous, yet they are successive. 

776. Some of the organs of the animal body-—the hands, 
the legs, neck, &c. — are subject to the exclusive control of 


BRAIN AND NERVOUS SYSTEM. 


339 


the will; they only move when directed by the brain. These 
are voluntary organs. There are others, such as the heart, 
stomach, &,c., which are not under the control of the will. 
They do not depend on our attention or volition to set them 
in motion, and no wish of ours can stay their actions. These 
are involuntary organs. The organs of respiration are both 
voluntary and involuntary. They act without our cognizance, 
and yet we can accelerate their motions, or entirely suspend 
them, by efforts of the will. The involuntary are supplied with 
nerves, both of sensation and of motion, as well as the volun¬ 
tary organs; but these nerves are not subject to our command. 

777. There are some motions which, though they are 
usually under the exclusive control of the will, yet at times 
are involuntary. We snatch the hand from burning by an 
effort of the will; yet if the fire be applied to it when we are 
asleep, and the action of the will is suspended, we snatch it 
away with a movement as involuntary as that by which the 
heart beats or the chest expands. The motions of the hand, 
the mouth, and the lower limbs, are ordinarily voluntary, and 
require a distinct volition for their execution; yet, in certain 
states of nervous disease, they become involuntary. They are 
then beyond the control of the will, and sometimes take place 
even when the will is opposed to them. In cases of epilepsy, in 
the St. Vitus’s dance, and in convulsions, the muscles are con¬ 
tracted, sometimes with great force, without volition, and the 
limbs are thrown about, although the sufferer struggles to 
resist it. 

778. There are other motions which are only effected by 
the direction of the will, which yet, by practice and disci¬ 
pline, become apparently, if not really, involuntary. Walk¬ 
ing and the playing upon a violin, an organ, or piano, require 
the constant attention of the mind of the beginner to excite 
and direct his movements. But after practice he can walk 
upon familiar paths, and play familiar tunes, without the ex¬ 
ertion of the will, and even while his attention is partially 
given to other matters. 

779. When motions become so familiar as to be executed 
without the attention of the mind, they fatigue the body less 


340 


PRACTICAL PHYSIOLOGY. 


than when they require the aid of mental action. Thus, 
when we walk, if we lift the foot and place it down at each 
step by a special effort of the mind, we shall be more wearied 
than when we walk, as we usually do, without a special vo¬ 
lition for each step, and have the mind free to attend to other 
matters. It is easy to see this difference of effect of exertion 
in the beginner and the practised performer of any work or 
art. The self-possessed dancer, who moves with careless 
ease through his figures, is less exhausted than the timid, 
cautious dancer, who anxiously watches every step. Both 
of these may move with the same energy, yet the one who 
added mental action and care to his muscular exercise drew 
more upon the nervous energies than the other, who exerted 
the muscles alone. 

780. Every function of every organ is dependent upon 
the nerves for its power. The tongue has a nerve of taste, 
one of common sensibility, and another of motion. The 
eye has one nerve of sight, another of motion. The secre¬ 
tions of the saliva, of the tears, and of the gastric juice, &c., 
are dependent upon their peculiar nerves to stimulate the 
processes. Each one of these operations must have its own 
nerve, and that must be in good health, and connected with 
the brain directly or through the spinal cord. If this ner¬ 
vous connection is disturbed or suspended, the function is 
impaired or fails. 


CHAPTER V. 

Brain presides over all Organs and Functions. — When it is impaired 
all Organs and Functions impaired. — Not sensitive. — Subject 
to Laws of Body. — When pressed, general Sensibility and Pow¬ 
er suspended. —Subject to Growth and Decay. — Has large Sup 
ply of Blood. — Change of its Particles increased by Exercise.— 
Fatigued with Action. — Sleep. 

781. The brain is the presiding genius over all the pow¬ 
ers and actions of life. It stands above all and over all, 
giving energy to, and directing the motions and operations 



BRAIN AND NERVOUS SYSTEM. 


341 


of, all the organs of the animal body. It is of the utmost 
importance in our structure, and, on this account, very great 
pains have been taken to provide for its well-being, and to 
defend it from injury. The thick bones of the skull are ar¬ 
ranged so as to give the greatest strength to the arch, and make 
it capable of bearing very heavy weights without suffering. 

780. The human brain fills all the cavity of the skull, and 
corresponds with its shape. It is the seat of sensation, of 
thought, and volition, and the organ of the mind. Through 
this we recognize the impressions of external things. These 
impressions, which are made upon the organs of sense, and car¬ 
ried inward through the nerve, are not perceived if the brain 
is wanting, or if its power of action is suspended. When it 
is unnaturally oppressed with blood, as in apoplexy, or with 
water, as in dropsy, the light that shines upon the eye is not 
recognized by the brain, and consequently the mind receives 
no idea of external objects which the light reflects. 

783. Although the brain is the organ of sensation , it is 
not of itself sensitive. It will bear pricking, or even cutting, 
with less pain than the fingers. Many experiments tried 
upon lower animals show that these creatures do not mani¬ 
fest signs of pain when the brain is cut, and even a part taken 
out. The same has been observed in man in cases of acci¬ 
dents. A child fell from a tree and fractured the skull; a 
part of the brain protruded, and the surgeon cut it off with 
out occasioning apparent pain. This has frequently been 
done with the same result, and when the mind was perfectly 
clear, and capable of attending to the impressions communi¬ 
cated to it through the brain. 

784. Whatever provisions are made by the Creator for the 
action and support of the brain, are as necessary for its well¬ 
being, and for the health of the mind, as the provisions made 
for the heart and lungs are for their well-being, and for circu¬ 
lation and respiration. It must have room for action. The 
cavity of the skull — its resting-place — is just large enough 
for it. It needs so much space, and no more, and does not 
safely bear any diminution. If this room be diminished by 

29 # 


342 


practical physiology. 


any thing which crowds the brain, the organ suffers. A sud¬ 
den effusion of water, or pressure of bone from fracture of 
the skull, or blood from apoplexy, immediately suspends its 
action, and then its functions, and those of the voluntary 
organs and the mind, are suspended; torpor and heaviness 
overwhelm the whole system. In other cases, where a tumor 
grow T s, or water is effused very slowly, the skull may expand, 
and still leave room for the brain; but in most of these in¬ 
stances, however slow their progress, the brain, sooner or 
later, suffers from the pressure, and then the physical and 
mental powers are impaired or suspended. 

785. Sir Astley Cooper relates a remarkable instance of 
a man whose skull was broken on a British man-of-war, in 
June, 1799, in the Mediterranean Sea. He was found in a 
state of insensibility, and incapable of voluntary motion, and 
he remained in this condition till May, 1800, when he was 
carried to St. Thomas’s Hospital, in London. There the sur¬ 
geon found a piece of bone forced in, and pressing upon the 
brain. When he removed this bone, the man recovered his 
sensibility, and was soon restored to health and activity, after 
having lived nearly a year in a state of unconsciousness.* 

786. The brain is subject to the law of growth and decay 
of its atoms. It requires nourishment of new particles and 
removal of the old, as well as all the other organs. It 
is therefore provided with an apparatus for nutrition and 
absorption, and arteries that bring the new blood, and 
veins that carry off the old blood and the wasted particles 
of matter. It seems to require more blood for its nourish¬ 
ment, and for the supply of its waste, than other organs of 
the same size, for it receives a much greater proportion than 
any other part of the body. The human brain receives from 
one fifteenth to one tenth of all the blood that flows in the 
body, and yet it weighs only about one fortieth of the whole 
frame. Its arteries, being a part of the general circulatory 
system, beat in the same manner and with the same frequen¬ 
cy as the arteries of the wrist. 

* Lectures on Surgery, Vol. I. p. 233. 


BRAIN AND NERVOUS SYSTEM. 


343 


787. Liebig says that action of the brain implies change of 
particles and waste, and, therefore, a greater supply of blood. 
To meet this increased want, the arteries beat with greater 
force, and send more blood, whenever the mind and the 
brain are excited or active. Sir Astley Cooper saw this in 
a young man who had lost a portion of the skull. “ His 
brain could be distinctly seen beating, through the opening 
of the skull; ” and, whenever he was irritated by any oppo¬ 
sition, the pulsation was much more violent, and it became 
more quiet when he was calm, and his mind was easy.* 
There was a girl in Montpellier, France, who had lost a large 
portion of the scalp and skull. Her brain could be seen for 
a considerable extent of surface. “When she was in a 
dreamless sleep, her brain was motionless, and low within 
the cranium; but when her sleep was imperfect, and she was 
agitated with dreams, her brain moved” and beat, more 
blood was sent to it, the arteries expanded, and the brain 
protruded through the hole in the bone. This protrusion 
was greater in active than in calm dreams; and when she 
was awake, the same difference was observed, consequent 
upon the activity and the quiescence of her mind. If she 
was in vigorous thought, the brain swelled, and protrusion 
was very observable.t 

788. The eye becomes weary with long exposure to 
light, and seeks rest and relief in shade; and, if not thus re¬ 
lieved, it finds it difficult to discriminate objects. The 
muscles, also, are fatigued with long and continuous exer¬ 
tion, and are incapable of contraction. Rest restores this 
power. So the brain is fatigued with long and uninterrupted 
attention to subjects of deep thought, and incapable of fixing 
its attention upon matters of a grave nature; then it wants, 
and must have, opportunity of rest to recover its energies; 
and, if this is not granted, the brain and the mind will be 
weakened or disordered. 

789. Sleep is the natural rest of the brain. It gives rest 
to the mind and to the voluntary organs of the body. The 

* Surgical Lectures. 

t Combe, 255. Annals of Phrenology, JNo. I. p. 39. 


344 


PRACTICAL PHYSIOLOGY. 


brain, and the nerves of sensation, and those that convey 
volition, sleep; but the motory nerves of the heart and arte¬ 
ries, and the lungs, never sleep. When a man dreams, his 
brain is not in complete rest; and, in the cases of sleep¬ 
walking, the sleep of the brain and of the nervous system is 
still less perfect, and of course the system is less refreshed 
by it. That sleep is most refreshing, and the best recruits 
the frame, in which there is neither dream nor motion, but 
absolute inaction of all the voluntary powers. 


CHAPTER VI. 

Night is the proper Season for Rest of the Brain. — Brain gains 
Power by Exercise. — Weakened by Over-Action. — Connected 
with other Organs; with Lungs, Stomach, Muscles. — Effect of 
Alcohol on Brain and Muscles } on Mechanical Skill; on Use of 
Tools. 

790. There is a natural connection of the action and in¬ 
action of the brain with the alternation of day and night. 
The brain, as well as the muscles, has more vigor and a 
greater power of action in the light of day, and is more prone 
to rest and to recruit itself in the darkness of night. The 
day is, then, the appropriate time for mental, as well as bodily 
labor, and the night the proper season for sleep of the mind 
and the brain. 

791. The stillness of the night, when the busy world is 
quieted, and we are secure from interruption, seems to in¬ 
vite the student to his books. Then the mind is not dis¬ 
turbed with other claims upon its attention, and there is 
then better opportunity for concentration of thought upon 
any subject. Therefore some attend to external matters 
during the day, or even sleep during some portion of it, and 
reserve their mental labor — the toil of the brain — for the 
night. It is an unprofitable habit of some clergymen to write 
their sermons in the evening or night before they must be 
delivered, and then, by concentrating the whole energy of 



BRAIN AND NERVOUS SYSTEM. 


345 


the brain upon their proposed labor, accomplish their work. 
This is frequently done, and with temporary success; but it 
is at the cost of the permanent power of the brain, as well as 
of the general health of the body. Naturally, the brain has 
the greatest power of labor, and the mind the greatest energy 
of thought, in the early part of the day, and less in the latter 
part, and least in the night; and consequently all mental 
labor exhausts the brain more in the evening and night than 
in the morning and the bright hours of day. 

792. The brain gains strength by moderate and appropri¬ 
ate exercise, when this is interchanged with rest; and, if 
frequently called upon to exert itself, it acts with greater en 
ergy, J ust as the muscles become strong with use, or the skin 
hardy with exposure. It is easy to see the difference of 
mental power in the laborer, — who uses his muscles, and not 
his brain, and works only under the direction of another, — 
and in the employer, whose brain is ever active with his 
plans of business. But excessive mental toil exhausts the 
power of the brain. Long-protracted labor of the brain, with 
insufficient or no intervals of rest, waste and weaken it; and 
any over-exertion, for even short periods, is injurious. The 
brain can bear excess of action no better than the muscles. 
The blacksmith or the stone-cutter can as safely do two days’ 
work every Saturday afternoon and night, as the clergyman 
can write his sermons in the same time. 

793. Although the brain is placed above and over all the 
other organs of the body, to give them life, and energy, and 
direction, yet it is dependent upon them for its own health 
and power. It has intimate connections and sympathies 
with each one of the others; it is strong with their strength, 
and weak with their weakness; it enjoys their pleasures, and 
suffers with their pains. 

794. The brain is constantly connected with , and imme¬ 
diately dependent on , the heart. It must have a large and un¬ 
failing supply of blood at any time. If the heart is dis¬ 
eased, and cannot admit the return of the venous blood, the 
brain is crowded with it; then pain and confusion, and even 


346 


PRACTICAL PHYSIOLOGY. 


insensibility, may follow. It needs and receives more blood 
during its action and excitement, and less in its quiescence 
and calmness. The heart must therefore be in good health, 
and able to supply the greater want of the active and excited 
brain. But, when the heart is diseased, it cannot send this 
increase of blood; and, if it attempts it, it struggles in vain, 
and great distress, and even death, may follow. Persons who 
suffer from disease of the heart, cannot safely bear any 
mental excitement. For this reason, a celebrated surgeon, 
who had this disease, continually guarded himself against 
any irritation of temper or agitation of mind, yet was sud¬ 
denly excited on an occasion, and immediately died. 

795. The connection of the brain with the lungs is not 
less apparent than with the heart. The brain needs not 
merely a large quantity of blood, but that of the purest and 
the best quality. Whenever the blood is imperfectly purified 
of its carbon, either from defect of the respiratory appara¬ 
tus or from want of pure air, the brain feels it immediately. 
If the waste and dead particles are not carried off from the 
blood in the lungs, the impure blood is sent again through 
the heart and arteries to supply the body; the brain suffers 
more than the other organs, and becomes inactive, and often 
painful, and the mind dull. The audience of a close and 
crowded lecture-room, and children in an unventilated 
school-room, lose their mental energy and their power of 
application. (§§ 383, 384, p. 165.) 

796. The sympathies between the brain and stomach are 
familiar to us. Most men have been compelled to know 
how these two organs suffer together in sick headache. The 
frequent pains in the head are generally to be referred to the 
derangement of the stomach, and, when this organ is relieved, 
the brain is usually well. Dyspeptics complain of much 
headache, and, on the contrary, those who suffer from disease 
of the brain are often troubled with digestive disturbance. A 
blow on the head will often occasion vomiting, and excess 
of action of the brain will sometimes suspend the action of 
the organs of digestion. 


BRAIN AND NERVOUS SYSTEM. 


347 


797. The brain controls the actions of all the muscles, 
and supplies them with the stimulus of motion through the 
nerves which connect them together. The muscles are thus 
completely dependent on the brain for their vitality and their 
energy. They can have no more life and energy than that 
controlling organ has to give them. If it is impaired, the 
power of muscular contraction is diminished. When the 
brain is pressed and incapable of action, the muscles are 
palsied and the limbs motionless. An injury of the head, 
which destroys sensibility, paralyzes the frame; and then the 
sufferer can neither stand nor move, for all voluntary action 
is suspended. It is the brain that directs every contraction 
of the muscles, and, by its complete discipline, harmonizes 
their actions so that the desired motions are produced in 
the limbs; and thus the movements of the musical performer, 
the skilful mechanic, and of the writer, are executed with 
beautiful precision. (§§ 636—640, p.276.) But if any thing 
disturbs the brain, and suspends or impairs its balance of 
action, n loses this control over the muscular actions, and 
they become irregular. 

798. Alcohol , in any of its forms , excites the brain and 
nervous system, and disturbs their actions, and impairs or 
suspends their control over the muscles. For this reason, 
the drunken man reels or staggers; he is unable to direct 
his feet and put them in the appointed places. Some of the 
muscles may contract too much, and others too little, and 
carry his feet too far, or not far enough, to one or the other 
side; or they may not contract even sufficiently to hold him 
up, and then he falls to the ground. When he attempts to 
work with his hands, he finds the same difficulty, the same 
want of control over the muscles that move the arms, hands, 
and fingers. He cannot direct them and the tools which he 
holds with the desired precision, and therefore often fails of 
striking the proper point. He may strike where he least 
intended, and do injury to his work or to his own person. 
The muscles of his tongue, also, suffer in the same way, and 
he articulates indistinctly. 


348 


PRACTICAL PHYSIOLOGY. 


799. After the brain and nervous system have been fre¬ 
quently excited, and their control of the muscular actions 
interrupted with stimulating spirits, they do not recover the 
complete command of the muscles when the fits of intoxica¬ 
tion pass away. Therefore old drunkards, even when sober, 
walk with a faltering step and work with an unsteady hand. 
They lose their power of skilful workmanship. If they are 
nice mechanics, they impair their skill by their intemperance, 
and are then compelled to apply their hands to coarser work ; 
and some are obliged to give up their handicraft altogether, 
and betake themselves to the rudest of common labor. 

800. I once knew a very skilful worker in iron. He was 
remarkable for the dexterous use of his hands, and the beauty 
and fitness of his manufactured articles. But he became in¬ 
temperate, and, after some years, lost the exact command of 
his hands, and the power of exact adaptation of his tools to the 
material on which he worked. He gave up his nice work, 
and manufactured coarser articles. In process of time, his 
muscles became less and less under his control, and he gave 
up his shop and trade altogether ; and, for the rest of his life, 
he sawed wood, dug in the ground, carried the hod for 
masons, doing nothing but the roughest work, which required 
the least discipline of the brain and command of the muscles. 

801 In this undisciplined condition of the brain, and ab¬ 
sence of command of the muscles, the intemperate man 
loses the power of self-protection, and consequently meets 
with more accidents than other men. When he walks, he 
makes missteps, he loses his balance, and stumbles over small 
obstacles. If he drives a nail, he is not sure to direct the 
hammer so as to strike the head; he may often hit his fin¬ 
gers. If he uses sharp tools, he may strike in a wrong 
direction, or his instrument may slip and cut his own flesh. 
A mechanic, when he wounded his knee with an axe, com 
plained to me of his frequent ill luck. He said he was 
always meeting with accidents. But a short time before, he 
bruised his finger with a hammer, while driving a nail; then 
he cut his foot; now he had cut his knee. He was intern- 


BRAIN AND NERVOUS SYSTEM. 


349 


perate; and, though not always intoxicated, — probably not 
so even at the time of his injuries, — yet he had lost the per¬ 
fect control of his muscular actions, and could not direct his 
blows safely 


CHAPTER VII. 

T rain Seat of Mind, Affections, Passions. — Power and Action of 
Mind limited by Power of Brain. — Stimulation of Brain stimulates 
Mind, and, on the contrary, Mind subject to Liabilities of Brain.— 
Impaired by Indigestion; by Excess of Eating; by Hunger.— 
Moral Feelings affected by Stomach. — Effect of Cheerfulness. 

802. The brain is the only avenue which the mind has to 
the outward world. It is the organ through which the intel¬ 
lect acts in regard to other minds and to external things. It 
is the seat of the passions, of the affections, and of the moral 
feelings. The immortal mind — the spirit itself— is, indeed, 
something more than, and different from, the physical brain ; 
yet the Creator has so connected these together in this life, 
that we know of the operations of one only through the me¬ 
dium of the other. As the eye is the organ of sight, and the 
ear the organ of hearing, so the brain is the organ of percep¬ 
tion, of thought, and affection. The eye is not sight, though 
there is no sight without it. The ear is not hearing, though 
there is none independent cf it. So the brain is not mind, 
though there is no mental operation without it. 

803. The brain being the only instrument with which 
the mind plays here, they are indissolubly connected to¬ 
gether in this life. Their powers of action have equal limits. 
Whatever we may say about the illimitable power of the ex¬ 
pansive mind, it can move no farther nor faster than the 
brain can go. Whenever the brain is weary, the mind is 
weary. Whenever the brain wants rest and sleep, the mind 
needs the same. The brain can make only a definite amount 
of exertion, and work only a definite number of hours, and 
then it must suspend all labor, and lie down to rest in com¬ 
plete inaction. The mind can do no more. Precisely at 

30 



350 


PRACTICAL PHYSIOLOGY. 


the point where the brain is fatigued, the intellect is fatigued, 
and when the brain sleeps, the mind falls into a state of un¬ 
consciousness. 

804. Whatever excites the brain excites the mind. The 
wine that first stimulates and then oppresses the nervous 
system, also at first quickens mental action, and then over¬ 
whelms the mind with stupor. Whatever stimulating sub¬ 
stance sends more blood to the brain, excites the mind to 
quicker action, and gives it a greater grasp of thought. On 
the contrary, whatever excites the mind to unusual action, oc¬ 
casions unusual flow of blood to the brain. The arteries of 
the brain were seen to beat (§ 787, p. 343) when the passions 
were irritated or the mind excited, and even when the sleeper 
was troubled with dreams. The blood flows in unnatural 
abundance through the brain of a man in passion, and of 
the scholar while he is studying with all his mental activity. 
The reverse happens when any emotion oppresses the mental 
energies. When one is appalled with fear, or depressed 
with sorrow, his countenance is pale with the absence of 
blood, and the brain is supplied in the same imperfect 
degree. 

805. The mind is subject to all the liabilities of the brain. 
It shares in all its sympathies with other organs of the body. 
When the brain is pressed with blood, as in apoplexy, or with 
a piece of broken skull, the mind is stupid. When the head 
aches from breathing foul air, the mind is dull; and it is 
torpid when one breathes charcoal gas. When alcohol 
gently increases the flow of blood in the head, the mind is 
more active, and the spirits more lively; and when this flow 
is a little more increased, and the brain stimulated too highly, 
the mind loses its balance, the thoughts run, and the tongue 
talks wildly; and a still further increase of blood stupefies 
the brain, and then the mind is torpid, and insensibility 
follows. 

806. I lately saw a child whose brain seemed to be torpid, 
but whose whole body was writhing in convulsions. The 
brain was oppressed, and the child was senseless; she could 


BRAIN AND NERVOUS SYSTEM. 


351 


neither hear, nor see, nor understand ; but the motory nerves 
were excited, and the muscles thrown into violent action. 
The child had eaten great quantities of unripe fruit, which 
the stomach could not digest. But as soon as the stomach 
was relieved of this unnatural load, the convulsions ceased, 
and the consciousness returned. But she had no recollec¬ 
tion of what had passed. Here was decided proof that the 
brain and nerves were connected with the digestive organs. 

807. Indigestion and nausea , which create pain in the 
head , impede mental action . When suffering from dyspep¬ 
sia, the student cannot apply his thoughts to weighty subjects, 
and the accountant is unwilling to attend to his figures, and 
make his calculations. Recently, a merchant, whose dinner 
oppressed him, found his mind so confused that he left his 
counting-room and went home to recruit his powers. Hav¬ 
ing a taste for grave matters, he attempted to read history; 
but he could not confine his attention to the subject. He 
then tried to read an exceedingly interesting biography — the 
ife of a friend ; but even this required too much mental ex¬ 
ertion ; and at last he betook himself to one of the lightest 
of tales, — Valentine Vox, — which he said required all the 
energy of mind that he could then exert. 

808. The same indisposition to mental exertion follows 
after eating an excessive meal. Great eaters, who keep their 
digestive organs constantly at work, have usually but little 
intellectual activity. They prefer sleeping to thinking, and 
study is a burden to them. On the contrary, hunger is none 
the less an enemy to mental labor, (§ 154, p. 73,) and in 
cases of extreme hunger, the mind cannot apply its powers 
to any matter of thought or business; and in starvation it 
loses its self-control entirely, and insanity sometimes follows. 

809. The moral powers and affections are influenced by 
the state of the digestive organs. A sour stomach produces 
a sour temper, and men are usually thought to be cheerful 
and good-natured while at dinner. Dyspeptics are frequently 
irritable and suspicious. They are sometimes gloomy, and 
look upon all about them with fear and distrust. A friend, 


352 


PRACTICAL PHYSIOLOGY. 


who is naturally of a kind and generous temper, but subject to 
occasional fits of painful indigestion, said, a few weeks since, 
that the world, at different times, wore two entirely different 
aspects, varying according to the state of his stomach. 
“ Now all is bright and promising ; I have an abundance of 
friends, and every body is kind ; I see nothing to mar the 
present, and feel no doubt of the future. But last week, when 
my stomach was in trouble, and my food oppressed me, every 
thing was as different as darkness from light. Then it 
seemed that I had no friends, and no one cared for me; the 
world was selfish, and gave me no sympathy nor encourage¬ 
ment; their actions and their speech were hostile to my 
character and peace. I put an unfavorable construction upon 
what was said to and concerning me. The very language 
that now seems to be that of kindness, seemed then to be in¬ 
jurious. The present was then full of doubt and fear, and 
the future promised nothing better. The cloud has now 
passed away, the sun shines brightly again in my heart and 
my prospects. It is all owing to the state of my stomach;” 

This is not an uncommon case. It may be frequently 
found, though perhaps in a less degree, and sometimes in a 
greater degree in the world. The connection between the 
indigestion and depression of spirit or suspicious temper 
is not so clear ; but it is none the less certain. 

810. On the contrary , the states of the mind and feelings 
affect the stomach and the other physical organs and their func¬ 
tions. Cheerfulness excites the respiration, and favors the 
purification of the blood. (§ 322, p. 143.) It aids the action 
of the heart (§ 235, p. 108) and the nutritive process through¬ 
out the body. But in sorrow and care, the respiration is 
languid, the purification of the blood imperfect, the heart 
moves heavily, and nutrition is sparing. Muscular power is 
increased and diminished by the same causes. The languid 
limb goes with the heavy heart, and the laborer works feebly 
whose spirit is weighed down with sorrow or discontent. 
(§ 713, p. 308.) Those who gain add more and more energy 
to their exertions, and those who labor unsuccessfully make 


BRAIN AND NERVOUS SYSTEM. 


353 


fainter and fainter efforts. These principles have been known 
from the times of old, when Solomon said, “ A merry heart 
doeth good like medicine, but a broken spirit drieth the 
bones.” 

809. The work of digestion goes on best in company with 
the warm and gentle affections, where love is predominant, 
and tenderness animates the soul. (§ 166, p. 78.) There 
the food is best converted into blood, and the blood into 
flesh, and this has most permanent power of action. But 
bitter and harsh feelings impair this work in all its processes. 
Fat people are usually supposed to be cheerful and contented 
with themselves and the world. They are not easily dis¬ 
turbed by the ordinary affairs about them. But the lean are 
usually more anxious and careful; they worry and fear more: 
they are not so easily satisfied, and are more affected by the 
mischances of every-day life. 

812. Thus there is a remarkable and a beautiful harmony 
between the flesh and the spirit. Cheerfulness and love add 
to the physical powers; and, on the contrary, robust health 
and bodily vigor aid in the buoyant flow of spirits. Melan¬ 
choly people are, therefore, usually less healthy and strong, as 
well as less happy, than the cheerful; and, moreover, they are 
more unprofitable workers. 


CHAPTER VIII. 

Brain superintends physical and mental Operations; sustains these 
well when it is vigorous, and several at the same Time, if they 
are easy, but not if they become difficult. — Mind works best 
when Body is easy. — Uncomfortable Seats interrupt Study.— 
Bad Light and Temperature, and Fatigue, have the same Effect. 

813. The brain superintends, or is connected with, the 
operations of all the organs of the body; both those which 
are involuntary and beyond the control of the will, and those 
30 * 



354 


PRACTICAL PHYSIOLOGY. 


which we direct by our volition. The movements of the 
limbs by the contraction of the muscles, the circulation of 
the blood, digestion, nutrition, respiration, the development 
of heat, the secretion of all the fluids, depend upon the brain. 
The mental and moral actions, the reception of knowledge 
through the organs of sense, thought, volition, the feelings, 
and the passions, are also connected with the brain. Every 
living action depends on the life of this organ, and every 
correct action depends upon its soundness. This organ and 
its powers are placed partially under our control; we think, 
we feel, we indulge in passion through it, and we direct its 
energies to muscular action. But it gives its energies to the 
involuntary actions without our will. We are responsible for 
the use of its power in all voluntary actions, and we may so 
use it as to interfere with its control of the involuntary 
actions. 

814. The brain performs all these offices well when it is 
fresh and yigorous; but, whenever the nervous energies are 
exhausted or reduced, the brain works languidly, and all the 
functions of the other organs also languish. When we are 
fatigued with muscular effort, digestion is feeble. (§ 162, p. 
77.) When the powers of the nervous system are diminished 
by excessive mental labor, the animal heat is sparingly gen¬ 
erated, (§ 434, p. 186;) or in whatever way the sustaining 
power of the brain is reduced, it is less able to support any 
of the bodily or mental operations, until it shall renew its 
power by sufficient rest. 

815. The brain sustains and superintends some of the 
voluntary, and all the involuntary, operations at the same time. 
We can walk, and breathe, and think, at the same moment, 
when neither of these requires any great effort or attention of 
the mind. But the brain cannot concentrate its power, so as 
to make any unusual exertion, upon more than one thing at 
a time. If, therefore, any one of these operations becomes 
difficult, or if we perform it with unusual energy, and conse¬ 
quently demand of the brain extraordinary power of direction 
or exertion, it can give but sparing energy and power to the 


BRAIN AND NERVOUS SYSTEM. 355 

performance of the other operations, (§ 708, p. 307,) or per¬ 
haps it must suspend them altogether. 

816. If any of the involuntary operations, which require 
the direction of the brain, but not the consciousness of the 
mind, becomes difficult, and requires mental effort, the brain 
can do little more than attend to it. Thus we maintain res¬ 
piration and carry on the other operations in conjunction 
with it; but in paroxysms of asthma, or in croup, when the 
whole nervous power is concentrated in the effort to breathe, 
all labor of body, and all thought must be suspended, and 
the whole nervous energy devoted to respiration. 

817. An accomplished musician can play several parts of 
a tune with his fingers upon the organ, and read and sing the 
words of the song, or call the figures of the cotillon; but if 
the tune is not familiar, — if it requires a special effort of the 
attention to read the notes, — he can neither sing the words of 
the song nor call the figures of the dance. 

818. If the brain is occupied by any other efforts, or by 
any disagreeable sensations, it cannot give its full attention 
to any mental operation. When a man wishes to give the 
undivided energy of his mind to any subject, he places him¬ 
self in such a position that his whole frame is most easy. If 
he sits, he selects a chair suited to the form of his frame, so 
that his body and limbs are supported without effort; and 
regulates the temperature of the room, so that he is neither 
hot nor cold; and the light, so that it is neither painfully 
glaring nor insufficient for the easiest perception. Some 
prefer a standing posture, and others will walk their rooms; 
but most prefer the sitting position while they are in intense 
thought; but, in either arrangement, nothing external calls 
the brain from the subjects of study. 

819. It is the fault of many school-rooms, that they are so 
constructed that a very considerable portion of the attention 
of the pupils is taken up with their uncomfortable physical 
sensations, and with their endeavors to obtain relief. Instead 
of the comparatively easy chairs, somewhat adapted to their 
forms, which children are accustomed to enjoy at home, these 


356 


PRACTICAL PHYSIOLOGY. 


school-rooms are usually furnished with seats of one kind, 
and nearly of one size, and made without regard to the hu¬ 
man shape. These seats are sometimes without backs, and 
sometimes with backs so square and perpendicular as to give 
no comfortable support. They are often so high that the 
smaller boys find no rest for the foot, or so low that the 
larger boys have not the usual support for the thigh. They 
are often built on an inclined plane, upon which the foot 
tends to slide forward and downward, and the child is then 
continually reminded of his position by his uncomfortable 
feelings, and is compelled to make constant exertion of his 
muscles to prevent his feet sliding forward. 

820. Some school-houses are so situated as to be pro¬ 
tected neither from the severest storms of winter nor from the 
burning sun of summer. They are often imperfectly warmed, 
and the temperature is unequal in the various parts. There 
are many whose chilly feet, in the cold season, make irresisti¬ 
ble drafts upon their attention; and, in the warm season, in 
the absence of both shade-trees and blinds, or curtains, the 
heat and the glare of the sun make equal claims upon their 
feelings, and withdraw their attention from their books. It 
is all in vain that their teachers urge upon them to study 
vigorously, and forget their discomforts, and that the good 
scholar, who is anxious for his lessons, does not regard these 
external matters. The physical sensations will come first; 
they will have the first care of the brain and the mind; and 
it is only by great mental discipline — such as few children 
possess—that they can be resisted and forgotten. And what¬ 
ever attention these suffering children give to the physical 
sensations is manifestly not given to their lessons. 

821. The same incompatibility exists between great fa¬ 
tigue and mental labor. While the nervous energies are 
devoted to restoring power to the muscles, they cannot be 
given to thought or reflection. The boy who is wearied 
with hard work before the hours of school, has not then the 
free command of his brain for his mental action. Very la¬ 
borious men are apt to fall asleep when they take up a book, 


BRAIN AND NERVOUS SYSTEM. 357 

or when they attend to a lecture or to a sermon in church, 
especially in the summer, when their toil is the most ex¬ 
hausting. This is a natural and necessary consequence. 
The mind cannot have the use of the brain when it is occu¬ 
pied with the restoration of exhausted physical power; for 
there is only a definite quantity of nervous energy, and, if 
this is expended in muscular action, it is gone, and cannot 
be given to mental labor. 


CHAPTER IX. 

Moral Feelings interfere with mental Action. — Anxiety and Fear 
prevent Attention to Business and Study. — Fear, and misdirected 
Hope, improper Motives for mental Action.—Best Motive. 

822. The mind cannot give its full and undivided atten¬ 
tion to observation or reflection while it is distracted or 
disturbed by any moral feeling. One who is anxious or in 
fear cannot easily study. Hence some become confused, 
and lose their self-possession, when they are in danger; they 
do not then concentrate their thoughts, and see clearly the 
actual circumstances of their case, or the means of relief. 
For the same reason, when one is riding with an ungovern¬ 
able horse, he may not command his muscles in the best 
way for his safety. Failing to perceive his true condition 
and means of escape, so as to direct his movements to this 
purpose, he may do the very things that increase his peril. 

823. Anxiety absorbs much of the energy of the brain, 
and prevents mental concentration; consequently, one can¬ 
not easily study, or give his mind to ordinary business, while 
he is anxious for the life of a parent or child, who is danger¬ 
ously ill. For the same reason, when men devote themselves 
to hazardous speculations, politics, or gambling, they often 
neglect their usual engagements, and lose, not only the con¬ 
fidence of their employers, but even the power of successfully 
managing their customary affairs. 



358 


PRACTICAL PHYSIOLOGY. 


824. The action of the same principle is seen in the 
school-room. When the boy is anxious about his play, or 
when any great and desirable purpose is before him, and 
especially if it be a matter of doubt whether he shall be per¬ 
mitted to enjoy it, his lessons may suffer. If a pleasant ex¬ 
cursion is proposed for the afternoon, provided the weather 
permit, and a cloudy forenoon render it uncertain whether 
a rain may not keep him at home, he cannot study well in 
this fear. The attention which the mind gives to the anxious 
doubt must all be at the cost of that effort which otherwise 
might have been devoted to his books. 

825. Whatever may be the kind of moral feeling, if it is 
strong, and absorbs the attention and power of the brain, it 
interferes with that concentration of the mind that is neces¬ 
sary to the study of books, or learning any other matters. 
The homesick boy, away from home, cannot give the full 
energy of his mind to his books, nor even to any labor. An 
active boy was sent from a very pleasant home to learn a 
desirable trade in an unpleasant situation and unkind family. 
Instead of giving his whole thoughts to his new business, he 
brooded over the joys and comforts that he had left behind 
him ; his heart was oppressed with sadness, and his yearnings 
for home occupied his mind. His employer thought him dull 
to learn, and lazy at work ; and, after several months of in¬ 
effectual trial, by common consent of his father and his 
master, he w T as taken away. At home, he again manifested 
his former activity and desire to learn the same trade, and 
was then sent to another and more satisfactory place and 
family, where every thing was kind and encouraging. He 
there showed great interest in his work, learned the art rap¬ 
idly, and became an unusually skilful and active workman. 

826. There are some seeming contradictions to this prin¬ 
ciple ; for many men have studied and become accomplished 
scholars when oppressed with pecuniary trials or bodily pains. 
Some of the best works in the language were written under 
the stimulus of poverty; and the late Robert Hall arose from 
his bed of acute distress to preach his most eloquent and 


BRAIN AND NERVOUS SYSTEM. 359 

powerful sermons. Some are so absorbed by their business 
or anxiety that they give no heed to impressions that would 
excite physical, and even painful sensations; while thus en¬ 
gaged, they may feel neither hunger nor cold, and forget the 
hour of their meals, (§ 87, p. 46,) or their chilled flesh. 

8*27. These persons, however, are exceptions to the gen¬ 
eral law. They had power of concentration sufficient to 
withhold their attention from the causes of physical and 
moral suffering. For the time, they forgot their painful sen¬ 
sations, or resisted the absorbing influence of their distress, 
and concentrated their nervous energies upon mental action. 
They have extraordinary power or discipline of mind, or are 
governed by an extraordinary motive to study or think amidst 
such counteracting influences. Nevertheless, these men 
bear a double burden — one in the disturbing cause, and 
the other in the intended labor of the brain; and, though 
they think and study much, they could do more if their 
minds were entirely free. 

828. It requires more mental discipline to study amidst 
these counteracting or disturbing influences. It needs a 
greater power of the will over the feelings to abstract the 
attention from all that would excite agreeable or painful 
sensations or emotions, and there are but few who possess 
this power in full degree. Yet it is to some extent neces¬ 
sary ; for, though one can study better when the body is 
perfectly easy, and the mind free from care, and the heart 
from pain, yet this condition is not always attainable. 

829. Even the motive offered as an inducement for action 
may become a disturbing cause, and absorb so much of the 
energy of the brain as to prevent, in some degree, the very 
effort it was designed to encourage. In this respect, both 
the motive of fear and of misdirected hope are often injuri¬ 
ous. When the iron rule prevails in school, the boy’s con¬ 
stant fear that he shall be caught idle, or that he shall fail in 
his lessons, or some unexpected accident or unpremeditated 
misdemeanor may happen and subject him to punishment, 


360 


PRACTICAL PHYSIOLOGY. 


makes some demand upon his brain, and withdraws so 
much attention from the subjects which he is required to 
learn. 

830. The motive of misdirected hope and of undue re¬ 
ward is often held out exclusively as a stimulus to greater 
and greater mental exertion. Whenever the reward does not 
grow naturally and necessarily out of the subject of study, it 
may interfere with its own purpose, and divide, rather than 
concentrate, the power of the brain and the attention of the 
mind. If, as an inducement to commit a lesson, or write a 
legible manuscript, the reward of a silver medal, or of a 
book, or an opportunity of declaiming before a public audi¬ 
ence, is proposed, the effect of division of thought and 
weakening mental effort follows. 

831. But the motives for mental exertion which belong 
to, or grow out of, the subject to be studied, not only with¬ 
draw none of the energies of the brain and the mind from the 
proposed object, and therefore neither divide nor weaken 
their exertions, but aid in concentrating all their force upon 
the single point of study. The value or the usefulness of 
the knowledge, or the advantage that must result directly 
from it, and, above all, the mere pleasure of learning, are, 
therefore, the most effective motives for, and auxiliaries to, 
mental labor. For this reason, boys who study with the idea 
that they are thereby to fit themselves for usefulness, re¬ 
spectability, and happiness, men who acquire professional 
knowledge, or learn science, as a means by which they shall 
obtain their support, or fortune, or station, or do good to 
others and, above all, naturalists and others, who study for 
the love of the sciences to which they give their attention, — 
are the most successful scholars. 


BRAIN AND NERVOUS SYSTEM. 


361 


CHAPTER X. 

Various Powers of Mind. — Strengthened by Exercise. — Education 
adapted to Powers. — Education of Children. — Mind cannot be 
prematurely strengthened. — Action of Brain needs Attention to 
other Organs. — Ill Health of Students. 

832. It is plain that there are various faculties of the 
mind , or the mind has power of application to various pur¬ 
poses ; and the commonest observation will show that these 
faculties are not equally strong in all persons. As the mus¬ 
cular strength is unequally distributed to the several limbs, 
so the mental and moral power is unequally distributed to 
the several faculties of different persons. Thus one man is 
strong for one purpose and weak for another. He may have 
a genius for mathematics, but little power to comprehend 
languages. He may excel in music, painting, or mechanics; 
he may be a skilful machinist or financier, and make great 
proficiency in any one of these subjects, while, in all others, 
he may not be above the average of men. In regard to 
these, as well as all other subjects to which the human mind 
is applied, there is a great difference in the mental power of 
men. This difference is partly native, and partly the re¬ 
sult of education. 

833. As the physical powers grow and become strong by 
proper use and exercise, and as any one of these becomes 
stronger than the others if it is more used than they are, so 
the mental and moral powers may be strengthened by similar 
means. All proper education is progressive, and is adapted 
to the state of the brain and mind which are to be educated. 
It begins with the strength and knowledge already acquired, 
and uses these as the means of acquiring more. Perfect edu¬ 
cation brings forth and strengthens all the mental and moral 
faculties, and gives them equal power. If these are original¬ 
ly unequal, they will require unequal care and exercise for 
their development. This plan of education of the various 
powers is also adapted to the natural order of their appear* 

31 


362 


PRACTICAL PHYSIOLOGY. 


ance. In this order, the appetites appear first, next the 
muscular power, then the senses, and lastly the moral and 
mental faculties; and a person successively eats, and moves, 
and observes, and reflects. 

834. The child enjoys the use of his senses. He wants 
things visible and tangible. His perceptive faculties are 
developed before his reflective. He observes before he rea¬ 
sons. He learns better from things that he can see and 
touch, than from descriptions of things which are not present 
to his senses. He can better give his attention to insects, 
flowers, and other natural objects, than to any abstract prin¬ 
ciples of which he may not see the application or the use. 
When these simple matters are taught, and the child learns 
the uses and the relations of sueh things as he can see and 
feel, and when these studies are sufficiently varied and inter¬ 
changed with muscular exercise and recreation, the brain is 
not fatigued, but, on the contrary, grows stronger, and able 
to undertake higher and more abstruse matters. 

835. In early life, the brain and the mind are feeble, like 
the other organs and powers, and are subject to the same 
laws of exercise and rest. Children love action, but they 
have little power of endurance. They dislike to confine 
their attention long to one subject. They are fond of 
change, for a variety of subjects exercises different powers. 
They are soon weary of one kind of play or work, and want 
another; they like to ehange their studies frequently; they 
prefer small books and short stories. But the most agreea¬ 
ble change for them is that of the powers and systems which 
are put in action. They love to use the brain awhile, and 
then the muscles, and then these both together. They like 
to study, then play, then work, 

836. The human brain, being subject to the same laws 
that govern the whole physical system, cannot be premature¬ 
ly strengthened and applied to labor, with more safety than 
the arm or the stomach. Its growth, from the earliest in¬ 
fancy to the maturity of manhood, is naturally slow and 
gradual; and it would be as injurious to attempt to force the 


BRAIN AND NERVOUS SYSTEM. 


303 


development of the infant mind, or induce it to make ex¬ 
traordinary exertions, as to impose upon the child’s hands a 
degree or weight of labor beyond its years. 

837. The brain and nervous system of most precocious 
children are unusually active; but often they are stimulated 
by injudicious education. In these cases, the nervous ener¬ 
gies, that should sustain the nutritive and the other systems, 
are absorbed in the mental labor. The mind may grow 
a while at the expense of the physical organs, and the child 
make great advancement in learning; but, in proportion as 
the brain is unnaturally excited, the other organs are deteri¬ 
orated, and the health falters, day by day, and the child may 
sink in death from over-stimulation of the brain, in accord¬ 
ance with that universal law which would have put an end 
to life if the stomach or the muscles had been unduly ex¬ 
cited and exerted to the same degree. 

© 

838. In youth and manhood , the brain cannot work long 
and vigorously without the health of the rest of the body. 
The organs are all linked together, and dependent one upon 
another. Each must have its due supply of nervous energy; 
if any one has more than this, — if it be stimulated to extraor¬ 
dinary exertion, — the others must suffer. Owing to inatten¬ 
tion to the physical organs, in connection with mental action, 
many students, and men in the sedentary professions, suffer 
from ill health. Ministers, lawyers, and teachers, are fre¬ 
quently obliged, from this cause, to suspend or give up their 
callings, and devote their whole attention to the recovery of 
lost health. 

839. Health fails more frequently among students than 
among men in the more active employments. More men 
leave college or quit their professions than leave any other 
callings on this account. This ill health among literary 
men is not the necessary result of their employments; it 
comes from the irregular distribution of the nervous power, 
and want of due cooperation among the various organs and 
systems that go to sustain life. 

840. There are many examples of the happiest and most 


364 


PRACTICAL PHYSIOLOGY. 


vigorous longevity in the pursuits of literature and science. 
Some ministers, lawyers, and physicians, have attended to 
their professional responsibilities until they were even more 
than fourscore years old. Most of the men whose vigor and 
usefulness were thus prolonged, manifested great activity of 
body, as well as energy of mind. Their mental powers were 
never idle. They were laborious in their vocations, and stood 
among the foremost as scholars. But with their great labor 
of the brain they judiciously combined due attention to the 
other organs and functions, and thus sustained their physical 
health. 


CHAPTER XI. 

Mental and physical Powers unequal in various Persons. — May 
be equalized by Education. — Inequality of mental Powers often 
increased by Education and Pursuits of Life. — Some excel in 
one Thing and are deficient in others; in mechanical Arts; in 
Morals. — Any mental or moral Power may be developed and 
strengthened. 

841. In some persons, the several systems have originally 
various degrees of power. The nervous, nutritive, or mus¬ 
cular system may be strong and active, while the others are 
weak and inactive. This inequality may be removed, par¬ 
tially or entirely, by judicious training, by exercising and 
strengthening those which are weak, and allowing the 
stronger to rest. For this purpose, the young man who has 
naturally strong and active brain, and weak muscles and 
digestive organs, needs the exercise of physical labor for his 
equal development, but is injured by much mental excite¬ 
ment ; while, on the contrary, the robust and vigorous, whose 
brain is sluggish, needs the stimulus of study, and can bear 
the physical inaction of a student’s life. 

842. The inequalities of the mental and moral powers 
may be removed by a similar principle in education, which 
exercises and develops the weak, and leaves the stronger 
faculties more at rest. But, by a mistake in the purposes 



BRAIN AND NERVOUS SYSTEM. 


365 


of education, a contrary principle is often adopted, and the 
strong faculties are made stronger and the weak weaker. 
Progress and acquirement seem to be the great object with 
some, and therefore they apply the main force of their minds 
to the subjects in which they make the easiest and most rapid 
advancement. If they have a taste for, or an extraordinary 
power of understanding, music, mathematics, mechanics, or 
general affairs, they give their attention to them, and neglect 
the others, for which they have less taste, and which they 
learn with difficulty. 

843. Whatever may be the cause that only a part of the 
faculties are exercised, and the others dormant, it is certain 
that those which are in active employment will be quick and 
comparatively strong, and give pleasure when in action, 
while the others are slow and weak, and act unwillingly, and 
even with pain. If the whole force of the brain has been 
directed to the cultivation or the action of one or a few 
faculties, the dulness and weakness of the others are about 
in proportion to the energy and activity of these. Hence, in 
the division of labor, a man becomes a more perfect work¬ 
man within his narrow sphere; but his range of knowledge 
is limited. 

844. Some men learn and perform, during their whole 
lives, only one operation in the mechanic arts. In this lim¬ 
ited sphere of action, they show exquisite workmanship; but 
beyond this they have neither knowledge nor power, and in 
the subjects of general interest they manifest great weakness 
and inactivity of intellect. In the manufacture of pins there 
were formerly twenty processes, and a man performed only 
one of these. From the beginning to the end of his working 
life, he exercised only the faculty of making one twentieth 
part of a pin, and if required to do any other work, or attend 
to any other subject of thought, he did it unskilfully, and 
with reluctance. 

845. The same is shown in the intellectual processes. 
Some men cultivate their memory to a remarkable degree, 
without a corresponding cultivation of the reasoning powers. 

31* 


366 


PRACTICAL PHYSIOLOGY. 


Their minds are grand storehouses of facts, which they do not 
know how to apply to useful purposes. Some have great rea¬ 
soning powers, but neither carefully observe, nor remember 
the facts that are presented to them. Some are very saga¬ 
cious in some kinds of business, to which they have given 
particular attention, and seem lost when affairs of other 
kinds are presented to them. 

846. The moral powers , individually , grow or suffer by 
the same treatment. If cultivated, they are strong and active ; 
and, if neglected, they are weak and sluggish. Some men 
are rigidly honest and sincere, but they are harsh and unkind. 
Others are the very reverse of these — gentle, affectionate, 
and full of benevolence, while they fail in justice and truth. 
The mind may be so exclusively devoted to one interest as 
to lose sight of the worth of others. A philanthropist may 
be so intensely absorbed in one kind, of human distress or 
one means of relief, as to think all other sufferings light, and 
other plans of relief unworthy of notice. 

847. In any time of life, the weak faculties may be 
strengthened, and the strong ones made stronger. However 
difficult any mental action may be at the beginning, it be¬ 
comes familiar and easy by frequent repetition. The faculty 
of memory, for instance, may labor hard at first, but, after a 
time, a man will commit pages with the same effort that he 
had exerted in acquiring as many lines. A young minister, 
taking charge of a church in the western country, — where 
clergymen usually preach without notes, — and yet not being 
accustomed to preach extempore, determined to write his 
sermons, and then commit them to memory, and thus avoid 
the use of his papers. At first, it cost him nearly as much 
labor to commit as to write his sermons ; but, after three 
years’ practice, the same work required only about an hour’s 
attention. 

848. The power of observation is very greatly quickened 
and strengthened by being constantly called into use. One’s 
eyesight becomes sharp, and he learns to recognize the mat¬ 
ters which he looks for. The practised seaman discovers a 


BRAIN AND NERVOUS SYSTEM. 


307 


sign of a storm, the hunter a track of game, and the botanist 
a flower, which escape the notice of the unpractised ob¬ 
server. A teacher of botany carried, in June, a box full of 
new flowers to a new but zealous pupil, who was much 
gratified with the sight of such a variety, and asked where he 
had found so many. “ On the road to the mill.” 4< I walked 
over the whole of that road,” said the scholar, “ and looked, 
as I thought, carefully for flowers, this morning, but could 
find only two.” 

849. Any one or more of the moral powers may be 
educated in the same manner. Self-command in times and 
scenes of peril comes by education, and is confirmed by habit. 
The new sailor climbs fearfully to the mast, and has hardly 
command of his muscles to assist in the management of his 
sails; but, after a few voyages, the same man will run over 
the rigging, and work there, even when the ship is violently 
rocked in the storm, with as much self-possession as if he 
were working in a shop on land. A painter’s young appren¬ 
tice crawls up the ladder with fearful agitation, and uses his 
brush with such timid caution that he touches over only a 
narrow surface on either side. But constant practice dis¬ 
pels all fear, and then he runs up the longest ladder without 
hesitation, and paints on either side to the farthest reach of 
his arms. 

850. In this development of the moral and intellectual 
faculties, teaching is the guide, and shows the way, and no 
more; but exercise gives them power. Learning the princi¬ 
ples alone will not make a man a musician, a mechanic, or 
a philanthropist. It will not fill his heart with love, cheer¬ 
fulness, or self-denial. The brain and the muscles, the mind 
and the hand, must be accustomed to the practice of these 
arts and principles, in order to make one skilful or virtuous. 
He who would be truly benevolent, must accustom himself 
to do kind actc,; he must not only know how, but he must 
be actually employed in relieving distress. Cheerfulness 
must be established by the same practical law. Men must 
not only believe in this rule, but they must habitually take 


368 


PRACTICAL PHYSIOLOGY. 


cheerful views of life, and always look hopefully upon the 
future. 

851. True politeness, which regards others’ feelings, and 
attends to their wants, becomes, by use, so ready a habit as 
to be almost a part of our nature. No principle nor motive 
can supply the want of this practice. If it is not a familiar 
habit, the politeness is artificial and awkward. It is very 
easy, in company, to see the difference between the cold and 
ungraceful manners of one who is unkind, and selfish, and 
clownish at home, but assumes gentle airs in society, and 
the easy and unassuming manners of another, who is ever 
the same, whether at home or abroad. The suavity which 
is assumed only for the public eye cannot conceal the harsh 
ness and coarseness of domestic habits. 


CHAPTER XII. 

Habitual Actions easy and agreeable. — Retired People averse to 
general Society. — Strength, gained by Exercise, preserved by 
same Means. — In perfect Men, all Powers developed. — Concen¬ 
tration of Mind. — Brain, when exhausted, needs Rest; cannot 
be overworked advantageously. — Vacations of Schools. 

852. Habitual actions are not only easy, but agreeable ; 
but those actions to which we are not accustomed exercise 
faculties which are not frequently employed, and are both dif¬ 
ficult and painful. We therefore perform them unwillingly. 
For this reason, many men prefer to associate and talk with 
others of the same pursuits, interests, or views of life; for 
conversation with them calls for the use of powers that are 
habitually active, and association with men of different char¬ 
acter would call for the use of powers that are usually dormant. 

853. Men who are unused to society are averse to gen¬ 
eral visiting, because miscellaneous conversation demands 
the exercise of inactive powers. They are therefore timid, 
and fear to trust themselves in the discussion of subjects 
with which they are not familiar, and in which, perhaps, 



BRAIN AND NERVOUS SYSTEM. 369 

they may falter. A few families, living in a retired district 
of the country, have associated almost exclusively with 
each other for two or three generations, and have had very 
little intercourse with the world, either at home or abroad. 
Their exclusive and familiar association has made their 
conversation upon the topics and interests of their little 
neighborhood easy and agreeable. But it has limited their 
ideas and feelings to their vicinity. Other feelings are 
dormant, and other ideas are strange to them. Conse¬ 
quently, conversation with men from other places calls upon 
their brain to attend to such matters, and make such exer¬ 
tions, as are neither familiar nor pleasant. They are, conse¬ 
quently, timid in presence of strangers, and suspicious of 
those whose habits of thought and notions do not harmonize 
with their own. 

854. The strength of the brain and the mind, or of any 
of its faculties, which is gained by exercise, must be pre¬ 
served by the same means. If this habitual activity of the 
mental or moral power is not kept up, it becomes again 
weak. The musician loses his skill, and the accountant his 
facility of reckoning, when out of practice. The bold man 
in danger becomes more timid after living a long time in 
secure places; the bold man in society loses his self-pos¬ 
session when he retires to obscure life; and the hospitable 
man entertains his friends with anxious hesitancy after he 
has ceased to keep open house. 

855. As in the perfect body all the organs are equally 
attended to, and all the muscles exercised, so in the perfect 
mind all the mental and moral faculties are developed, exer¬ 
cised, and strengthened, in due proportion. Washington 
was a remarkable instance of this equality and completeness 
of physical, mental, and moral character. None of his 
powers were dormant, and none had excessive growth. All 
were subject to the control of his will. This mental and 
moral fulness and discipline give men command of their re¬ 
sources, and great power in every emergency. They are 
thus prepared for the various chances of life. They meet 


370 


PRACTICAL PHYSIOLOGY. 


with few difficulties, and always overcome them. They are, 
therefore, the most successful and the happiest men. 

856. If all the mental faculties are faithfully cultivated 
and exercised, the mind acquires its greatest strength and 
power of universal application. But one thing more is 
wanting; that is, the power of concentrating the whole men¬ 
tal energies upon a single subject, to the exclusion of all 
others; that is, the power of the will over all the physical 
organs, over the instincts, and the passions, and the mental 
faculties. 

857. This mental discipline subdues not only all the phys¬ 
ical and moral, but the mental powers, to the control of the 
will, and enables us to concentrate the whole force of the 
nervous system upon one object, and exclude all others; 
otherwise, the mind is frequently wandering from the sub¬ 
ject proposed to it. The possession or want of this control 
of the mind — this power of concentration — constitutes one 
great difference between the strong and the weak mind — 
the rapid and the dull scholar. 

858. It is the misfortune of many students that, while 
they fix their eyes upon their books, their thoughts are afar 
off, upon their play, their home, or their pleasures. They 
look upon their lessons in school; their eyes run over a page 
of history at home; every line, every word, is presented to 
the organ of vision; but no sensation is excited in the brain, 
the mind receives no ideas. Another, with better mental 
discipline, withdraws his mind from all but the subject before 
him; and, while he is reading or studying, he thinks of 
nothing else, — all other thoughts are excluded, and his 
whole mental force is directed to the matter about which he 
is reading; and thus he loses no time, and wastes no mental 
effort. Every exertion aids him in his advancement, and he 
is therefore a successful scholar. 

859. The brain has the same desire and enjoyment of 
exercise as the muscles. The child runs and plays, and 
observes and talks; and the man, if he has no occasion for 
motion, will walk for exercise; and, if he has no call for 


BRAIN AND NERVOUS SYSTEM. 


371 


thought or observation, he will yet read, — perhaps only the 
lightest books, such as require the least exertion of mind, — 
or he will talk, if of nothing more important, he will tell of 
the news of his little neighborhood, or he will sit at his 
window and watch the passengers in the highway. In some 
way or other, the brain is frequently exercised, though often 
in the gentlest way. There are few who sit long in entire 
listlessness, without a thought or an emotion. This would 
be as painful as to sit immovably still for any considerable 
period, without moving a limb. 

860. The brain has the same liability to fatigue from 
labor, and exhaustion from excess of exercise, as the mus¬ 
cles. It has a definite power of exertion, beyond which it 
cannot pass, without leaving it enfeebled. If its action is 
confined within this due limit, and sufficient opportunity is 
given, at proper intervals, for its recovery, it will never fall 
below its average standard of effective labor, and it will be 
able on each day to do a full day’s work. But, if this limit is 
exceeded, its strength is reduced so far below its own stand¬ 
ard, that it is not recruited in the allotted time of rest, and 
consequently is unable to perform even the usual work on 
the following day. 

861. In December, 1842, I had occasion to write several 
hundred letters, and wished to finish them as early as possi¬ 
ble. With the average industry, I could write thirty a day, 
without being fatigued beyond the power of the night to re¬ 
store my mental energies. But, feeling over-anxious to finish 
the work, I began one morning at six o’clock, and sat at my 
desk until twelve at night. Within these eighteen hours, 
I wrote fifty letters, and then, exhausted in mind, I retired 
to rest, but did not readily sleep — the brain, being much 
excited, was not easily quieted. The next day, I was too 
weary to write, and wrote none. That day was entirely 
lost; and even on the third day I fell short of my thirty 
letters; consequently, I lost more than I gained, by this vain 
attempt to overwork the brain. 

862. When the brain has thus been in long and active 


372 


PRACTICAL PHYSIOLOGY. 


labor, its excitement does not subside readily with the cessa¬ 
tion of work. It is then useless to attempt to sleep. The 
nervous energies, thus stimulated, must have some vent, 
either by light reading, conversation, or some gentle mus¬ 
cular exercise. An eminent lawyer in Massachusetts, who 
was employed, during the sessions of the court, in an almost 
continuous succession of cases, and whose brain was excited 
to unremitting labor from morning till late at night during 
this period, found it impossible to sleep immediately after 
his labors ceased, although he was much fatigued. He 
therefore accustomed himself to walk for some time, after 
leaving the court-room and before going to his chamber. 
With this preparation, he slept comfortably, and awoke on 
the following morning refreshed and prepared for renewed 
labor. 

863. It would be well so to arrange our business and 
studies, that the brain should be required to work and ex¬ 
pend no more energy in each day than it can recover at 
night. In this way, it would be able to perform as much on 
the day following, and on each successive day thereafter, and 
need no long periods of rest throughout the whole of life. 
But this is not usually done. Our business, our schools, 
and colleges, are arranged upon the erroneous plan of doing 
more than a day’s mental work in each day during the busy 
season or term time, and of having intervals of rest in vaca¬ 
tions. This arrangement of mental action and rest is ordi¬ 
narily made, not in reference to health and power of the 
mind to labor, but to convenience, or pleasure. Some col¬ 
leges and schools have long terms and long vacations, to 
allow the pupils to visit their distant homes. The mind be¬ 
comes weary, and works languidly, in the latter weeks of 
these long terms, and the habits of study are broken up in 
the long vacations; and neither is so advantageous for 
mental action and health as short and more frequent periods 
of labor and rest. 


BRAIN AND NERVOUS SYSTEM. 


373 


CHAPTER XIII. 


Digestive and Mental Powers vary. — If this be disregarded, Diges¬ 
tive and Mental Disorder may follow. —- Mind disordered by Dys- 
'psia; Cold; Heat; Over-Action. 

864. It is well known, that the digestive organs are not 
alike in all persons. One cannot eat some kinds of meat, 
another cannot digest some kinds of vegetables, a third is 
sickened with some kinds of fruit, while a fourth eats of 
all these, and obtains nutriment and comfortable health from 
each. So long as these persons avoid that food which in¬ 
jures them, they eat freely and maintain their health. But, 
if any one eats that which he does not digest easily, he 
suffers from pain; and, if he perseveres in eating it, his 
stomach becomes deranged, and then digests nothing easily. 

865. So it is with the mind, which is not equally strong 
for every purpose. If its attention and actions are confined 
to the purposes which it can accomplish, and if it avoids all 
others which it cannot master, it manifests no disorder. But 
when it is required to attend to or comprehend such subjects 
as are beyond its power, or assume responsibilities which 
are impossible for it to bear, it struggles to do this with 
pain, and is wearied with the effort; and, if the attempt is per¬ 
sisted in, the mind is weakened, and sometimes becomes 
deranged. 

866. Some men transact their usual business, and fulfil 
their responsibilities, discreetly and successfully, but when 
they go out of their ordinary paths, and engage in political 
strife or religious excitement, or when they suffer from 
grief or from the unprosperous turn of their worldly affairs, 
their minds lose their balance and become deranged. Many 
others pass through the same excitements, or are afflicted 
with similar troubles, without mental disorder. Those who 
fall, had some previous weakness of mind which prevented 
their enduring what the others endured in safety. They 

32 


374 


PRACTICAL PHYSIOLOGY. 


became insane, therefore, in circumstances which were harm 
less to their associates. 

867. The immediate sympathy between the other organs 
and the brain compels it to feel their ills, and to be often¬ 
times deranged with them. Pains of the head and confusion 
of mind are connected with the sickness of the stomach. 
Insanity sometimes rises from dyspepsia. In such cases, 
even during convalescence, the mental disorder is brought 
back by renewal of the digestive trouble. Any error in 
diet, any improper food, too hearty meals, or gas in the 
stomach, excites the brain; then the old delusions again 
return, and the mind suffers acute distress until the stom¬ 
ach is relieved. 

868. The suppression of evacuations to which the sys¬ 
tem has become accustomed sometimes disturbs the brain, 
and causes mental derangement. Even the closing an 
ulcer which has been running for a long time may produce 
the same effect. 

869. Very great cold confuses the brain, and deranges 
the mind. Captain Parry, in the journal of his voyage to 
the Northern Ocean, states, that, when his men were exposed 
to extreme cold, they seemed to have lost their power of 
mind, and upon one occasion, when some of his men re¬ 
turned from an expedition in which they had suffered from 
great severity of weather, they were confused, and stared 
vacantly and wildly. They could give no account of them¬ 
selves, nor of their late conduct; but, after they recovered 
their natural temperature, they regained their clearness of 
intellect. Similar instances are given in Fremont’s journal 
of his second expedition over the Rocky Mountains. A 
high, as well as a low temperature, usually affects the mind 
unfavorably. Mania is sometimes caused by exposure of 
the head to great heat. 

870. Very frequent causes of insanity are connected with 
the abuses of the mental and moral powers. As dyspepsia 
arises from errors in diet, — from the wrong purposes to which 
the digestive organs are applied, or from the excessive bur- 


BRAIN AND NERVOUS SYSTEM. 


375 


dens imposed upon them, — so insanity follows the wrong 
application of the powers or the excessive labors of the 
brain. When the mind is required to attend to and com¬ 
prehend subjects beyond its powers, or manage affairs beyond 
its control, or when it is compelled to work too long upon 
any one subject, which it can manage to a moderate extent, 
it must falter, and be liable to irregular action. 

871. When we fix the eye for a long and uninterrupted 
period upon any single object, the organ becomes weary, and 
fails to receive clear impressions, and convey them to the 
brain. If this is done frequently and perseveringly, the eye 
becomes weak or diseased, and ceases to perform its func¬ 
tions. In the same manner, the brain, by over-exertion, is 
wearied, and refuses to give its attention. When this undue 
labor has been continued for a long time, without proper 
intervals of rest, the mind becomes exhausted, and it loses 
its self-control and its power of direction, and cannot be 
roused to any satisfactory exertion. It is then permanently 
weak and uncertain in its operations. 


CHAPTER XIV. 

Insanity, from misdirected Education, and false Hopes; from un¬ 
founded Expectations; religious Anxiety; perverse mental Habits. 

872. Misdirected education, the preparation for pur¬ 
poses which cannot be attained, or stations which cannot be 
filled, impose upon the mind an excessive burden, and in¬ 
volve it in a profitless struggle, and often entail upon it 
weakness, and sometimes disease. All wrong notions of 
life necessarily end in disappointment. They are based 
upon false views of the world and of the relations of society, 
and lead men to look for such events as will not happen in 
the circumstances which must surround them. The flat¬ 
tered child of popular favor, who expects to find amid the 



376 


PRACTICAL PHYSIOLOGY. 


responsibilities and cares of riper age the same adulation 
and caresses that come to the careless joyousness of earlier 
years, and who confidently expects that the future will bring 
him a measure of success and prosperity for which he is not 
now making an adequate preparation, must meet with dis¬ 
appointment, and suffer the consequences of sorrow and 
perhaps of mental disturbance. 

873. All those expectations which are founded in hope 
rather than on calculation, which depend upon uncertain 
and inappreciable chances for their gratification, and excite 
the imagination strongly, must often fall short of their fulfil¬ 
ment. Speculation in property of variable value, in con¬ 
fidence of great profits; mining in those regions where no 
human sagacity or foresight can tell whether the ore can be 
found, or obtained at profitable cost; the doubtful struggle 
for situations of honor or profit, — are all attended with great 
anxiety; and when they fail, as they frequently must, the 
spirit sinks and the mind may wander. 

874. Religious anxiety, or the struggle of the mind in 
the transition from old to new conditions or opinions, is 
occasionally productive of mental disorder. When the 
mind has given up the old foundations on which it rested 
its hopes and its confidence, and before it has adopted the 
new, upon which it can securely stand, it seems to be un¬ 
loosed from its hold, and thrown upon uncertainty. Persons 
in this condition lose their self-control; the world and its 
cares and enjoyments, and the future, with its promises 
and its threatenings, change their aspect, to them, and they 
may be overwhelmed with distress. If then they can see 
their way clearly to a better life, the excitement passes 
away, and the mind is easy; but if this light does not 
appear to them, they may fall back to their former con¬ 
dition, or become a prey to more abiding and painful de¬ 
rangement. 

875. The natural appetites may be so pampered, or arti¬ 
ficial appetites may be created and may grow so strong, 
that we cannot control them. The appetite for intoxicating 


BRAIN AND NERVOUS SYSTEM. * 377 

drinks is among the most powerful in its influence over 
those who indulge it. This is not a natural want. It is 
artificially created and encouraged, until it is strong enough 
to take care of itself and compel its gratification. It is then 
in vain that the man thinks and says, he will not desire to 
drink; the stomach and the nervous system are so changed 
as to kindle and keep up this burning thirst for alcoholic 
stimulants. The man may have moral force sufficient to 
prevent the gratification, but one may as well say that the 
parched tongue of fever shall not be dry and crave cold 
water, as that the stomach, excited and disordered by in¬ 
temperance, shall not thirst and crave its accustomed in¬ 
dulgence. 

876. The irregular habits of the mind sometimes over¬ 
power the will. Some individuals exhibit a propensity to do 
strange things, and to utter startling opinions. They have a 
fondness for attracting attention by their oddity of manners, 
or thoughts, or language. At first, these singularities are 
assumed and put off at pleasure ; but, if they are allowed to 
come often, they establish a habit which cannot be resisted. 
The man is then compelled to exhibit his oddities at times 
when he would be glad to appear like other people. In 
other matters, his brain and his mental operations may be 
manageable, and he may be sound in mind; but so far as he 
cannot or does not regulate his thoughts, his mind is not 
sound. 


CHAPTER XV. 

Day-Dreaming. — Fits of Passion. — Intoxication. — Fright may 
cause Insanity. — Various Grades of mental Health between Sani¬ 
ty and Insanity.— No sound Mind without sound Body. — Most 
Causes of mental Disorder within our Control. 

877. Some take great pleasure in day-dreaming. They 
love to abstract their minds from the facts and things about 
them, — from subjects of real existence, — and, creating an 
32 * 



378 


PRACTICAL PHYSIOLOGY. 


imaginary world, surround themselves with a train of circum¬ 
stances from which unpleasant things shall be excluded, and 
nothing but the agreeable be near them. In such a world, 
they determine what they would do and say, what principles 
should govern them, and what impressions they would make 
upon their associates. Thus they revel in this delightful 
revery, where all is beautiful and satisfactory. 

878. This habit of revery grows more easy and inviting, 
so that the mind insensibly falls into it when not otherwise 
occupied. Then the will loses its power to exclude it, and 
direct the thoughts to the mixed realities of life, until, at last, 
the dreaming becomes irresistible, and the dreamer can no 
longer control his wandering mind, nor see things as they 
are. For a period, — perhaps for years, — he governs his 
imagination in presence of others, and conceals his dreams 
from the world. But the habit grows stronger, and finall), 
regarding neither men nor circumstances, it will speak out 
and when the dreamer talks as he thinks, and uses strange 
language, and perhaps exhibits strange conduct, he is ac¬ 
knowledged insane. 

879. When the mind has been strongly excited, the law 
of continuance prevents its immediate return to rest, and we 
think of those matters that intensely interested us, after the 
time of their action has passed away. We cannot dismiss 
immediately strong sensations, and feelings, and thoughts; 
and, if they were violent, they may remain for a long period. 
The agitation of fright continues after the cause is removed. 
As blindness, partial or total, may arise from the glare of 
intense light, so the mind, when confused with terror, or dis¬ 
turbed with powerful irritation, may not recover its clear¬ 
ness and self-control, but remain disordered. 

880. Men under the excitement of passion lose their self- 
control, and perform acts, and give utterance to language, 
which, in their calm moments, they would not willingly 
allow in themselves. If these passionate excitements are not 
checked, they gain more and more power to subdue the will, 
while the resolution to resist grows weaker. Gradually, the 


BRAIN AND NERVOUS SYSTEM. 


379 


subjection of the will to the excited feelings increases, the 
mind is made insane from slighter causes, and the derange¬ 
ment is longer continued, until this disorder is fixed, and the 
passionate man is a maniac. 

881. Whether the brain be unduly excited by mental 
action, or by any physical stimulant, the result is the same — 
mental derangement. Intoxication with alcohol creates a 
powerful operation on this organ, which is plainly an irregu¬ 
lar and uncontrollable one. The drunken man has no more 
power over his thoughts than the maniac. Usually, after a 
fit of intoxication passes away, the brain recovers its self- 
possession, and the mind is restored to health; yet some¬ 
times this complete restoration does not take place, and the 
mind of the drunkard continues weak and irregular in its 
action, and he is then a lunatic. 

882. It is not to be supposed that all these causes pro¬ 
duce insanity, or that this disease must always follow these 
violations of the natural laws. But there is a wide differ¬ 
ence between the clear and well-disciplined mind, that can 
be directed at will, and understand and reason correctly, 
and is buoyant with cheerfulness, and the mind that is to¬ 
tally deranged with lunacy, or overpowered with melancholy. 
And in this wide interval there are all grades of mental 
health and power. The mind that is excited with alcohol 
or passion, or depressed with fear, is incapable of the clearest 
perceptions of the true and the reasonable. The brain that 
is torpid after an excessive dinner, or that is in pain from 
dyspepsia, is, for the time being, deprived of its full power 
of action. Anxiety, grief, disappointment, and day-dream¬ 
ing, absorb some of the nervous power, and prevent the free 
and untrammelled range of thought. These, and all other 
habits and conditions that diminish or absorb any of the 
nervous energy, so far as they lay any tax upon the strength 
or the labor of the brain, or interfere with its free operations, 
oppress or excite the mind. 

883. It will now be plainly seen that there is no sound 
ness of mind without a sound brain, and that disorder of any 


380 


PRACTICAL PHYSIOLOGY. 


or all of the other organs may derange the nervous system, 
and produce mental derangement. It is also manifest that 
the abuse or neglect of any of the passions, propensities, or 
mental faculties, may produce the same result, in greater or 
less degree, of disordered mind. Most, if not all the causes 
of partial or total insanity, come within our cognizance, and 
are originally within our control. The brain and the mind 
are as subject to fixed laws as the other organs, and it is left 
for us to see that the conditions of their life are fulfilled, 
and that we enjoy, not only general and open mental health, 
but, under every circumstance, and in every moment of our 
lives, in secret as well as in public, we possess full mental 
strength, and the clearest power of thought, and the most 
perfect control over our feelings and passions. 


EYE. 

CHAPTER XVI. 

Eye. — Situation. — Composition. — Humors. — Lens. — Coverings. 
— Iris. — Pupil. — Effect of Light. — Lids. — Tears. — Lachrymal 
Apparatus. — Muscles. — Cross-eye. — Optic Nerve. 

884. The eye is placed in a deep , bony socket in the skull. 
This socket extends far backward at the base of the brain, 
and defends this tender organ from blows and accidents on 
every side except the front. 

885. The eyeball is composed of three substances. 

The aqueous, or watery humor , (Fig. LXVI. b,) is a clear, 
transparent fluid, and stands in the front of the eye. 

The vitreous humor forms almost the whole of the globe, 
(Fig. LXVI. d.) This is atransparent substance, and soft like 
a jelly. It is enclosed in a very delicate membrane, which 
covers its outside, and, extending through it, forms many 
cells, which contain this humor. 



EYE. 


381 


The crystalline lens stands between the vitreous and the 
aqueous humors, (Fig. LXVI. c.) This is a double convex 
lens, much more dense than the vitreous humor, and holds its 
shape without any covering. It is composed of concentric 


Fig. LXVI. Section of the Eye. 


a, Coats of the eye. 

b, Aqueous humor. 

c, Crystalline lens. 
d y Yitreous humor. 
e, Cornea. 



f f Iris. 
g, Optic nerve. 
hy Retina. 


layers like those of an onion, which can be removed one from 
another. In the fish, this lens is globular. In man, it ap¬ 
proaches flatness. 

886. Three membranes or coats enclose these humors, and 
retain the eye in its globular shape. 

The outer, or sclerotic coat, like the dura mater of the 
brain, is very firm and strong, and able to resist considerable 
force without being broken. It covers almost the whole eye. 
It has a large aperture in front, in which the cornea is placed, 
(Fig. LXVI. e.) The cornea covers the front of the eye. It is 
transparent and strong. It projects in the shape of a watch 
glass, and covers the aqueous humor. 

887. The middle, or choroid coat of the eye is very delicate 
and soft. It contains a black pigment, which absorbs such 
rays of light as are not needed for vision. 

888. The third or inner coat is the retina , which is prin¬ 
cipally the expansion of the optic nerve. This receives the 
rays of light from the objects which are presented to the eye. 

889. In the front part of the eye are, 1st. The cornea. 
2d. The aqueous humor. 3d. The iris and pupil. 4th. The 
crystalline lens, and then the vitreous humor. 

The iris is a very delicate circle, or continuation of the 
middle or choroid coat, (Fig. LXVI./,/.) The pupil is an 


382 


PRACTICAL PHYSIOLOGY. 


aperture in the centre of the iris. The iris is expansible and 
contractile : when it expands, it extends toward the centre, 
and lessens the diameter of the pupil; and when it contracts, 
it draws back from the centre, and enlarges the pupil. By 
this means, the amount of light received into the eye is regu¬ 
lated. When we are in a dark place, the iris contracts, the 
pupil is enlarged, and more rays are admitted. When the 
light is increased, the iris expands, the pupil is contracted, 
and fewer rays are admitted. When we first go from a bright 
light, as from a well-lighted room to the darker air abroad in 
the evening, we see with difficulty, because the pupil is so 
small that few rays can enter the eye. But soon the pupil 
enlarges, more rays enter, and we see with ease. On the 
contrary, when we go suddenly from a dark to a very light 
place, the pupil being large, much light enters, and the eyes 
are dazzled; but soon the iris expands, the pupil diminishes 
and fewer rays enter, and we bear the light without incon 
venience. 

890. The lids protect the eyes in front. They are com 
posed of cartilages adapted to the shape of the eye, the skin 
without, and the lining membrane within. The lining of the 
lids is continued over the front of the eye. It prepares and 
throws out upon itself a thin mucous or glairy fluid, that oils 
the surface and allows the lids to glide smoothly over the ball. 
One circular muscle surrounds the open part of the eye, (Fig. 
LII. &,) and closes the lids when it contracts. Another mus¬ 
cle, attached to the upper eyelid by one end, and to the bone 
of the socket by the other, opens the eye. 

891. The tears wash the eye and keep its surface clean. 
The apparatus for this purpose consists of the lachrymal 
glands, tubes, ducts, and canal. The lachrymal glands are 
placed in the upper and outer corner of the socket, (Fig. 
LXVII.a.) They prepare the tears, which then flow through 
the ducts (Fig. LXVII. h) under the upper lid into the eye. By 
the motions of the lids the tears are spread over all the surface 
of the eye, and wash away any particles of dust. Then they 
fall into a little groove or trough in the upper edge of the 


EYE. 


383 


lower lid, and flow along to the inner corner of the eye. There 
they are received through very small apertures into the lach¬ 
rymal canals, and then they pass through the nasal duct (Fig. 
LXVII. d , d ) into the nose. 

Fig. LXVII. 


a, Lachrymal gland. 

b, Lachrymal ducts. 

c, c, Lachrymal canals. 

d , d, Nasal duct. 


892. The lachrymal canals are sometimes inflamed and 
closed, and the passage for the tears into the nose is thus 
stopped. The tears then find no outlet, and flow over upon 
the cheek, causing some irritation. 

893. This apparatus sympathizes with the moral affections. 
The tears are prepared in the gland, and flow more abun¬ 
dantly than they can be received in the canals, in grief, and 
sometimes in joy, and then they flow over the cheeks. 

894. The eye is rolled by a set of muscles peculiar to itself. 
These are attached by one end to the bony socket, and by the 
other to the eyeball. By their contractions they roll the eye 
in every direction ; and, by their cooperation, both eyes are 
directed to a single object. 

895. In cross-eyed persons , these muscles do not work in 
harmony ; some one acts more powerfully than the correspond¬ 
ing muscles, and draws one eye to one side more than the 
other: this is most commonly inward. 


Lachrymal Apparatus. 



384 


PRACTICAL PHYSIOLOGY. 


896. The optic nerve (Fig. LXVI. g) passes from the base 
of the brain forward through the socket and into the eyeball. 
After passing the outer and middle coats, it is spread out on 
their inner surface, and forms the retina, which receives the 
rays of light. 

Fig. LXVIII. Muscles of the Eye. 



a , Part of the bony socket. 

b, Optic nerve. 

Cy Eyeball. 

d, Muscle that raises the upper 
lid. 

e, g. Muscle that passes from 
the socket at a, through the loop 


f, and back to the ball. It rolls 
the eye downward and outward. 

h, Muscle attached to outer 
edge of the bony socket, and to 
the side of the ball. It rolls the 
eye upward and inward. 


897. The eye is thus complicated, with many and various 
parts, all of which are arranged and harmonized together, 
and all adapted to the action of light without, and to the per¬ 
ceptive power of the brain within. 

The light is reflected from objects, and passes through the 
transparent cornea and the pupil into the ball. The humors 
and the lens refract these rays, and give them such a direction 
that they fall upon the retina, where they form the image of 
the object. This impression is carried along the optic nerve 
to the brain, and there perception takes place and the object 
is seen. 



EYE. 


385 


CHAPTER XVII. 

Near-sightedness. — Spectacles to be worn cautiously. —Eye-Glasses 

injurious. — Far-sightedness.—Eye suffers with other Organs.— 

Needs Cleanliness. — Bathing. — Pure Air. — Sufficient Light. — 

Rest. 

898. The eye is subject to very many and various derange¬ 
ments, which impair vision in various ways and degrees. 

Near-sightedness is one of the most common defects of vis¬ 
ion. This arises from various causes. It is most frequently 
produced by the habit of looking at very near objects ; as in 
reading, writing, engraving, sewing, &,c., when the books, 
papers, or work are held close to the eye. In persons so em¬ 
ployed, the eye so habitually adapts its focus to these near 
objects, that it is difficult, or even impossible, to adapt it to 
objects at a greater distance. 

This defect may be avoided or lessened by being much 
abroad and accustoming the eye to look at distant objects, 
landscapes, scenery, &c., and also by holding the , books or 
the work as far from the eye as possible. 

899. In this disorder, the lenses are supposed to be too 
round. They refract the rays too much, and concentrate 
them, and form the image, before they reach the retina. 

Concave spectacles obviate near-sightedness. They give a dif¬ 
ferent refraction to the rays, and throw the image upon the ret¬ 
ina. When they are used, and especially when they are worn 
constantly, the eye makes no effort to accommodate its focus 
to distant objects, and remains permanently near-sighted, and 
frequently the difficulty is increased. But if spectacles are 
omitted as long as possible, and then used only occasionally and 
for seeing distant objects, leaving the eye to its own resources 
for all near and household objects, the evil would not tend to 
increase, and the eye would enjoy a wider range of vision. 

900. Spectacles covering both eyes affect them equally, 
and give them the same focus. But eye-glasses being used 
for only one eye, makes that more near-sighted than the other, 
and these organs, therefore, have unequal power of vision, 

33 


3S6 


PRACTICAL PHYSIOLOGY. 


901. Far-sightedness is a defect of age, when the eye loses 
the power of adapting its focus to near objects. The lens 
loses its convexity in some degree, and the rays are not con¬ 
centrated upon the retina. This evil is obviated by the use 
of convex glasses, which give the rays the proper refraction, 
throw the image upon the retina, and enable the eye to see 
near objects distinctly, 

902. The eye suffers with the rest of the body. The sight 
is best in vigorous health, and is impaired by many diseases. 
Some disorders of the eye have their origin solely in dis¬ 
orders in distant organs. A troublesome affection, called 
muscce voliiantes, or flying flies, is sometimes caused by in¬ 
digestion merely. The dyspeptic then sees flies or motes, or 
little clouds, that seem to be flying before his eyes. These 
are owing to the state of the retina, which is frequently caused 
by the state of the digestive organs; and when the stomach 
is restored to health, the flying flies are gone. 

903. The eye wants the utmost cleanliness for its health. 
It should, therefore, be bathed and kept free from dust and 
other matters. It is benefited by the bath as well as the 
skin. It is well to dip the face every morning, with the eyes 
open, in cold and clear water, and then to move the lids and 
thus wash the surface. This should be done daily, and 
oftener when exposed to dust or other offensive matters. 

904. The eye needs fresh and pure air. Those who live 
in the foul air of crowded dwellings and shops, or in the 
smoke of some rooms, often have disordered vision. 

905. The eye is made for , and should be accustomed to , the 
light. Those who work in dark shops, or live in dark streets 
or houses, or in parlors closely darkened with curtains and 
blinds, and women who wear veils to shut out the free light 
of day, have comparatively weakened vision. 

906. The eyes need light for vision , and suffer or lose their 
power in some degree when required to labor in insufficient 
light. Thus they are injured when used for reading, sewing, 
or examining any minute objects by twilight or moonlight, or 
in any insufficient light, by day or night. All imperfectly 


EAR. 


387 


lighted apartments, counting-rooms, houses and shops in dark 
alleys, or with insufficient windows, weaken the vision of 
those who study, write, or work in them. 

907. The eyes suffer from protracted exertion in the same 
way as the brain and the muscles. They become wearied, 
and even sometimes disordered, from looking long at objects 
that require minute attention, as reading fine print, engraving, 
miniature portrait painting, sewing, &,c. Those who are 
employed in such things would do well to give their eves 
change of occupation and rest. 


EAR. 

CHAPTER XVIII. 

Composition. — External Ear. — Position. — Not to be covered. — 

Ear-Wax. — Membrane of the Tympanum. — Eustachian Tube.— 

Bones of the Ear. — Labyrinth. — Nerve. — Requisites of hearing. 

— Air. — Healthy Ear. — Attention. — Deafness. — Causes. — Hear¬ 
ing may be cultivated. — Ear for Music. 

908. The organ of hearing includes the external ear, which 
is on the outside of the head, the passage to the tympanum or 
drum, and the internal ear, which is within the drum. 

909. The outer ear is composed principally of a somewhat 
stiff cartilage, that retains it in its shape. 

The shape of the outer ear is that which is best adapted to 
catch sounds and transmit them to the internal ear. This 
form has been adopted by skilful mechanicians, to gather 
sounds in rooms and transmit them to other and distant 
places. 

The ears of the lower animals are differently shaped, accord¬ 
ing to their different purposes. The human ear is scarcely 
movable; but, in some other animals, it is moved to catch 
sounds in different directions. 



3S8 


PRACTICAL PHYSIOLOGY. 


910. The human ear , in its natural condition, stands out 
from the head at a considerable angle. This position gives 
it the greatest advantage for catching sounds. But the cus¬ 
tom of wearing caps and other head dresses, and the manner 
of dressing the hair, press the ear near, and in some persons 
close to, the head, and thus diminish their acuteness of 
hearing. 

911. The entire external ear stands open for the reception 
of sounds ; but when any of its parts, or the whole, is covered 
with the hair or any dresses, the access of sound is obstructed, 
and the hearing somewhat impaired. 

Fig. LXIX. Ear. 


a, a, External Ear. 
by Opening to the internal ear. 
c, Canal leading to the drum. 
dy Membrane of the tympanum. 
e, Semicircular canals. 

/, Snail-shell, or cochlea. 


912. The external canal or meatus , (Fig. LXIX. c ,) opens 
from the external to the internal ear. It is about an inch 
long. Its course is not straight nor direct, but somewhat for¬ 
ward and curved. There are many little cells in its lining, 
in which the ear-wax is prepared. There are, also, hairs 
about this canal. The wax and the hairs protect this canal 
from the entrance of insects. 

The ear-wax is sometimes secreted in so great quantity as 
to fill the canal, and prevent the access of sound. 

913. The membrane of the tympanum , or covering of the 
drum of the ear , is spread across the bottom of the canal and 









EAR. 


389 


closes it. This very delicate membrane separates the canal 
or middle ear from the internal ear. 

914. The cavity of the internal ear is behind the membrane 
of the tympanum. This cavity is filled with air. It has no 
outlet to the external ear. But there is a passage or tube, 
called the eustachian tube, which leads from the back part of 
the mouth to the cavity of the internal ear. The air has free 
access from the mouth to the inner ear through this tube. 

The air may be forced from the mouth through this tube 
into the internal ear, by closing the lips and the nostrils, and 
pressing the air from the lungs through the windpipe. The 
air is then felt pressing into the ear with a sound, and some¬ 
times with a loud sound. The acts of gaping and swallowing 
have a somewhat similar effect; the latter creates a distinct 
murmuring, and the former a sort of explosive sound in the 
inner ear. 

This tube holds the same relation to the drum of the ear 
as the hole in the side of a martial drum does to that musical 
instrument. When the vibration of the air strikes upon the 
membrane of the tympanum, the air within receives the im¬ 
pression, and partly escapes through the eustachian tube, and 
thus the impression is modified. 

915. There are within the drum of the ear three small hones , 
which are so arranged as to connect the membranous cover¬ 
ing with the labyrinth, &,c., where the auditory nerve is 
spread, and to convey the impressions, which are made by the 
undulations of the atmosphere on the outside of the membrane, 
to the nervous filaments within. 

916. There are also three semicircular canals , (Fig. LXIX. 
c ,) and the cochlea , (Fig. LXIX./,) which have their use in 
the function of hearing, but precisely what use, it is not easy 
to explain. These are placed within the parts of the bone at 
the side and the base of the head. 

917. The auditory nerve passes from the brain through a 
hole at the bottom and side of the skull, and is spread about 
in the labyrinth of the ear. 

918. All the several parts of the car are adapted to receive 

33* 


390 


PRACTICAL PHYSIOLOGY. 


the impressions made by sonorous bodies, and to convey them 
to the brain. The sonorous body causes vibrations in the air. 
These vibrations strike upon the membrane of the tympanum. 
The membrane acts upon the series of bones, and through 
them upon the internal parts and the branches of the auditory 
nerve, and then along this nerve the sonorous impression is 
conveyed to the brain, where sensation is caused, the sound is 
perceived, and the noise is heard. 

919. It is necessary, for hearing sound, that there should 
be a sonorous body to create it, air to convey it, the healthy 
ear to receive, and the brain to perceive it. 

920. There can be no sound where there is no air. If a bell 
be rung in an exhausted receiver of an air pump, no noise is 
made. The sound is more or less loud according to the state 
of the air. It is conveyed more distinctly and farther in the 
direction of the wind than in the opposite course, or in any 
direction when the air is still. Thus we hear the sounds of 
bells, &c., when they are at the windward better than when 
they are at the leeward from us. 

921. It if necessary that the parts of the ear should be 
sound for perfect hearing. When the outer canal of the ear 
is filled, or the membrane of the tympanum is covered, with 
wax, hearing is impaired. 

922. The eustachian tube is sometimes closed. Inflam¬ 
mation of the throat, from colds, may extend to the lining of 
this tube, and prevent the free passage of air. When this 
happens from this or other causes, we feel an uneasy fulness 
and pressure within the ear, and noises have an unnatural and 
unpleasant sound. 

When this tube is closed from slight and temporary causes, 
it can be opened by gaping, or by pressing the air into it from 
the lungs. 

924. Hearing is impaired, and deafness, in various degrees, 
arises, from very many causes, and from diseases in other 
organs as well as those within the ear. Worms in the diges¬ 
tive organs, scarlet fever, measles, small-pox, and influenza 
sometimes produce this effect. 


CONCLUSION. 


391 


925. Hearing requires the active attention of the brain and 
the mind ; and deafness or imperfect hearing may be caused by 
the mere habit of neglecting impressions received by the ears. 

926. The faculty of hearing may be cultivated to a very 
high degree. The practised hunters and the American 
Indians, who are trained to attend to and catch very slight 
and distant sounds, can hear the natural voice of animals and 
men, or their footsteps, or even their breathing, or other 
noises indicating their existence, when others hear nothing. 

927. The ear for music or power of distinguishing har¬ 
monies of sound, is partly a natural gift, and partly a matter 
of cultivation. Almost all have it in some degree, and some 
in a very high degree. And there are very few in whom it 
may not be increased by education. 


CONCLUSION. 


Man responsible for Care of his Health. — Strength and Weakness, 
and Length of Life, given according to Man’s Faithfulness. —In¬ 
tention of Nature that we live happy and long. — Power lost by 
Sickness. — Life shortened. — Errors in the Management of Health. 
— Constitution impaired in various Ways. — Effect of Education 
and Circumstances on Constitution. 

928. The human body, with its complicated structure 
and organs, is left in the charge of man. He is appointed to 
take it as it comes from the hands of the Creator, and de¬ 
velop and exercise it, direct its actions, supply its wants, and 
govern all the appetites, according to the requirements of life. 
These conditions are exact and unyielding, and the good 
or evil consequences are certain to follow their fulfilment or 
neglect. In ratio of our obedience will be the fulness of life, 
its strength, its comfort, and its duration. We can have no 
health except so far as we obey the law. We can relax in 




392 


PRACTICAL PHYSIOLOGY. 


no required exertion, omit no necessary supply, and indulge 
in no wrong appetite or propensity. However small the 
error, the ever-watchful sentinel of life visits it with a propor¬ 
tionate punishment, either of positive pain or lessened en¬ 
joyment. 

829. Various powers are given to us, and all are necessary 
to our being and happiness. The animal powers and wants, 
the appetites and propensities, give pleasure when used and 
gratified in suitable degree. The moral and intellectual 
powers give a higher enjoyment. As the mind needs the 
body for its earthly home, so the body needs the mind as a 
director. The bodily health is preserved by acting in obe¬ 
dience to the intellectual and moral faculties, and the mental 
exercise required for this management of the body is neces¬ 
sary for the health of the brain. 

930. These, then, are the intentions of Nature — that we 
lead long, full, and happy lives; that, from the beginning to the 
end, we have neither sickness, nor weakness, nor discontent¬ 
ment; and that our bodies attain their fulness of strength, 
and preserve it to a good old age; that all our faculties be 
developed and strengthened in the performance of the duties 
of life, and every day be filled with uninterrupted faithful¬ 
ness or unalloyed pleasure. It is plain that we fall short of 
all these blessings of life. 

931. Between complete life and death there is a wide 
interval, in which there are many degrees of health and 
strength; and so accustomed are men to the lower degrees, 
that they seldom look for the higher, but seem generally con¬ 
tent with less. But there is a point in which there is a ful¬ 
ness of physical, intellectual, and moral power. This, and 
this alone, is perfect health. 

932. It is rare that any one passes any considerable period 
without some sickness so severe as to compel him to suspend 
his usual employment, and give himself up entirely to the 
work of recovery. Sickness and weakness, in one form or 
other, seem to be expected as the occasional lot of all; and 
much of our time, power, and comfort, is thereby lost. 


CONCLUSION. 


393 


But the whole amount of these which we lose by sickness 
that prostrates us, is much less than the amount of those lost 
by the many lesser ailments or debilities which impair our 
energies and diminish our ease in small degrees, and for 
short periods, and thus lay light, but very frequent taxes 
upon our vitality. There are hours or days when we have 
colds, headache, pain or stiffness in the limbs; when we are 
heavy and inert from indigestible or over-abundant food, or 
other causes; when we are timid or irresolute, irritable, peev¬ 
ish, or melancholy; when we have not the full control of all 
our faculties, because the body or the mind does not willing¬ 
ly, or cannot, direct all its energies to our intended purpose 
These, individually, make but slight deductions from the 
force, the productiveness, and the enjoyments of life; yet, 
when added together, their sum is very great. 

933. Not only are the power and the value of life very 
materially diminished in its course by the greater, and lesser 
sicknesses and indispositions, weakness, and languor, but life 
itself is shortened by these and other causes connected with 
our existence. The natural period of human’ life, in favora¬ 
ble circumstances, is supposed to be seventy years; yet com¬ 
paratively few reach that term. The average duration of 
life differs in different countries. According to the bills of 
mortality, the average age of those who died in Massachusetts 
was 33 years and 8 months; in Sweden, 29 years; and in 
Russia, a little less than 20 years. This average of life dif¬ 
fers in different localities. In some towns in Massachusetts, 
it is upwards of 40 years, while in others it is but a little more 
than 30. There is still a wider difference in the duration of 
life in the various classes of society even in the same place. 
In England, the average duration of life of the families, in¬ 
cluding the parents and children, among the most favored 
classes, was, in Liverpool, 35; in Rutlandshire, 52; and in 
Wiltshire, 60 years; and among the poorer classes it was, 
in Liverpool, 15 ; in Rutlandshire, 38; and in Wiltshire, 
33 years. Wherever the same examination has been made 
in this country, a similar difference in the duration of life 
has been shown. 


394 


PRACTICAL PHYSIOLOGY. 


934. Thus we see that the most favored people fall short 
of the full period of their earthly existence, and the poor in 
some places do not average one fourth of it. If we add to 
this abbreviation of life the deductions made by the lighter 
and temporary indispositions, and the severer and protracted 
sicknesses, and deduct the whole from the allotted period of 
threescore and ten years, it is manifest that a large part of 
mankind receive but a small share of the amount of active 
and productive life that seems intended for them. 

935. This great abridgement of life is not caused by im¬ 
perfection of the Creator’s work. There is nothing in the 
healthy organization that indicates the necessity of disease, 
debility, or early death. Nature has not made the mistake 
of giving man a set of organs, all of which may continue in 
successful operation seventy years, with the exception of the 
lungs, or stomach, or brain, which will wear out, or become 
disordered and fail, in half that time. These are not the 
mistakes of nature; for, with the exception of hereditary dis¬ 
eases and imperfections which some parent has engrafted on 
his own constitution and transmitted to his children, most 
men are born with perfect and equal organization, with 
equal power of action and endurance in all the parts of 
their frames. 

936. Few die, at the end of their full period, from ex¬ 
haustion of all their physical powers by proper and regular 
action through the whole period. Most men die before the 
natural term is completed, from the failure or disease of the 
respiratory or digestive organs, of the heart, or brain, much 
more frequently than from general disease of the frame. 
During five years, in Massachusetts, 8882 died of diseases of 
lungs, 6076 of diseases of digestive organs, 3718 of diseases 
of brain and nervous system, and only 3048 of old age. 

937. Here is a very small portion — but little more than 
one tenth — that died because the machinery of life was worn 
out. The great majority died from the disease or failure of 
some one of the organs to sustain itself and perform its part 
in the work of life. If these organs had originally equal 


CONCLUSION. 


395 


power, and were prepared to perform equal work, there must 
have been some variation from, or failure in the conditions 
of being. This failure of any one or all of the organs may 
arise from one of two causes — from some deficiency of the 
building up the body, in the development and strengthening 
of its organs, or from some mistake in the expenditure of its 
powers. 

938. Strength should be constantly added, by means of 
food, air, exercise, &<c., and a portion of this strength may 
be expended through the muscles, or the brain and nervous 
system. We may err in the building up the body, by sup¬ 
plying it with insufficient, innutritious, indigestible, or exces¬ 
sive food, or with impure air. Or we may repair the vital 
machine with two much cost of nervous power, or with the 
wear and the waste of the organs of supply. To this daily 
repair of the body some strength must be given. This re¬ 
pair must be attended to before any other matters; and, if it 
be faithfully made, it will generate more strength than it 
consumes, and leave a surplus portion to be devoted to 
other purposes. 

939. The energy, or power of the body for its self-suste¬ 
nance, and for its action beyond itself, is what is called the 
constitution. This vital constitution, in regard to health 
and action, may be likened to capital in trade, and the sur¬ 
plus power of action may be considered as its income. 
That amount of income, or surplus strength, which is gath¬ 
ered daily, and no more, may be daily expended. But if 
the expenditure exceeds the income, and more strength is 
expended than is gained, it draws so much upon the capital, 
or the constitution, and then the body must lie still and rest, 
to regain its loss. 

940. There are manifold ways in which the gathered 
power may be expended, — in mental labor, or muscular 
exercise, in grief, irregularities and intemperance of every 
sort, excessive action of the digestive organs, stimulation 
of alcohol, excitement, passion, exposure to cold, &c. In 
most of these ways, a limited amount of power may be 


396 


PRACTICAL PHYSIOLOGY. 


expended, and leave the capital unimpaired; but any excess, 
however small, like an excess of expenditure of money over 
the income, must be taken out of the constitution. All 
failure in the building up, all privations of nutriment, of 
sleep, or of due exercise, or bathing, however small, in¬ 
asmuch as the body is thereby strengthened less, produce 
so much less income, and create a deficiency of the vital 
power. 

941. The excess of expenditure of strength, in every way, 
over the daily income, and all deficiency in strengthening, 
then, wear upon the constitution. In these many ways, the 
deterioration may be very slight and imperceptible at the 
time ; the evil consequences may not be great enough to 
call our attention to them; yet the power of life is dimin¬ 
ished, there is less energy in the action of the organs, and 
less power to resist causes of disturbance. Each one of 
these errors diminishes the capital of life in proportion to its 
extent. One takes a little, and another a little, and yet the 
loss is unnoticed until the whole, added together, weakens 
the constitution, impairs the health, and wastes the strength 
so much, that some other cause creates a perceptible dis¬ 
order or pain, and this we call disease. This may be fatal, 
not because of its own force or violence, but because the 
vital force had been previously so much reduced, that it 
could not resist this cause of disturbance. Thus the system 
is not only laid open to attacks of disease, but its power of 
overcoming it is lost; as men’s affairs are sometimes embar- 

I rassed apparently by a new debt o^ loss, but really because 
their capital had been diminished so much by previous mis¬ 
fortune or mismanagement, that the new obligation is an 
insupportable burden. 

942. The natural and artificial varieties of human con¬ 
stitution are variously affected by education, habits, cir¬ 
cumstances, employments, and localities. These influences 
may be so used as to diminish, and often remove, these in¬ 
equalities, or, on the contrary, to increase and establish them, 
[f they are carefully regarded in the training of children 


CONCLUSION. 


397 


and youth, in the selection of occupations or places of resi¬ 
dence, the weak may become strong, or a part or organ that 
cannot be strengthened will not be compelled to bear a 
burden beyond its powers. But, owing to neglect of this 
principle, the circumstances of life are often so used that the 
weak organs become weaker; the inequality is thereby in¬ 
creased, and the health is impaired. The robust and the 
feeble, the nervously-excitable and the lymphatic, obviously 
need different employments. Those who have weak lungs, 
and inherit predisposition to consumption or asthma, cannot 
safely engage in the same pursuits, or inhabit the same 
localities, which would be beneficial to one of more perfect 
organization. Thackrah, in his valuable work on the Influ¬ 
ence of Employments on Health and Longevity, says that 
not fifty of the fifty thousand who annually die of consump¬ 
tion in Great Britain, would fall by this disease, if proper 
occupation and habits were adopted. The dyspeptic needs 
an active, and not a sedentary avocation; and the nervous 
suffer if the brain is called into excessive exercise by study, 
or the anxious cares of business; and those who are subject 
to catarrh and asthma are made worse by working in the 
dusty trades or places. 

943. Out of our own organization, and with the external 
means offered to us by a generous Providence, we are to 
sustain our health and prolong our life. For this purpose, 
as a judicious engineer first learns the structure, and uses, 
and power of his machine, and then supplies all its materials, 
adapts the surrounding circumstances to its wants, and gov¬ 
erns its movements, and applies its powers precisely to its 
intended purposes, so, in the management of our vital ma¬ 
chine, we must first learn its structure, powers, and wants, 
and then supply the one and direct the other precisely 
according to the law of life, this responsibility for the 
care of the body and the mind comes upon every one, in 
every condition; and whosoever discharges it with intelli¬ 
gence and faithfulness, will increase his powers and his 
enjoyments, and have length of days on earth. 

34 


























. 


■ 


. 




QUESTIONS 


ON 

. JARVIS’S PRACTICAL PHYSIOLOGY. 

PREPARED BY 

EV. SOLOMON ADAMS, 

OF BOSTON, MASSACHUSETTS. 


PART I. 

DIGESTION AND FOOD. 

CHAPTER I. 

1. What changes take place in the animal body from birth to man¬ 
hood ? 

2. What law is impressed on all animal beings? 

3. What makes food necessary? 

4. What is the difference between food and living flesh ? 

5. What is the process of this change? 

6. What organs constitute the digestive apparatus? 

7. What offices do the several parts of the mouth perform in the 
digestive process? 

8. What teeth have carnivorous animals? 

9. What teeth have herbivorous animals? 

10. To what kinds of food are the teeth of man adapted? 

11. How many teeth, and what kinds, has man? 

12. How are the teeth set in the jaw ? Of what are they composed ? 
What causes their decay ? 

13. How may the cause of decay be prevented ? 

14. Why are decayed teeth painful ? 

CHAPTER II. 

15. When do the glands of the mouth secrete saliva ? 

16. When do the glands refuse to perform this office ? 

17. What must be done to food before it is swallowed? 

18. Describe the second chamber of the mouth. 


( 399 ) 



400 


QUESTIONS ON 


19. How many passages open from this chamber ? What are they ? 

20. Where is the mouth of the windpipe ? What is the epiglottis ? 

21. What are the offices of the epiglottis ? 

22. Why can we not breathe when swallowing? 

23. Describe the oesophagus or gullet. 

24. How does the oesophagus move the food towards the stomach ? 


CHAPTER III. 

25. Describe the stomach ? Why is it always full ? 

26. On what does the average size of the stomach depend ? 

27. What is the texture of the stomach ? Of how many coats is it 
composed ? Describe the outer or peritoneal coat. 

28. Describe the middle or muscular coat. 

29. The inner or mucous coat. 

30. What familiar illustration of these coats ? 

31. What office do these coats severally perform in the digestive 
process? By what is the food dissolved in the stomach ? 

32. How is the gastric juice prepared ? 

33. What effect has the gastric juice on all proper kinds of food ? 

34. What opportunity had Dr. Beaumont? 

35. 36. What observations of Dr. Beaumont have made known the 
steps of the process? 


CHAPTER IV. 

37. Do Dr. Beaumont's observations explain the process ? or only 
reveal the several stages of digestion ? What advantage results from 
a complete mastication ? 

38. In what quantity is the gastric juice secreted ? 

39. What is the limit of this secretion ? What is the consequence 
of this limit? 

40. Have we any measure of the amount of food which we ought 
to take at a meal ? How can this measure be ascertained ? 

41. What condition is necessary to make this measure a guide ? 

42. What is hunger? When felt? 

43,44. Give the illustration. 

45. When does the work of digestion begin ? How long is the gas¬ 
tric juice secreted ? 


CHAPTER V. 

46. What is the relative position of the stomach, lungs, and dia¬ 
phragm ? 

47. How does respiration keep the stomach in motion ? What effect 
has this motion on digestion? 

48. To what substance is all the food reduced in the stomach ? 

49. What temperature does digestion require ? 

50. Relate Dr. Beaumont’s experiments. 


jarvis’s practical physiology. 401 

51. What inferences may be drawn from these observations on the 
temperature of the stomach? 

52. What part of the stomach first receives the food from the mouth ? 
What is the pyloric valve ? What is its office ? 

53. What power of discrimination does it seem- to possess ? 

54. How does it treat improper food ? What is our sensation at such 
times ? 

55. How does this struggle between the stomach and the pylorus 
end ? What are the effects ? 

CHAPTER VI. 

56. Are all articles of food digested with equal ease ? 

57. What is the average time which a healthy stomach requires for 
digestion ? 

58. Give the results of observations on St. Martin, in relation to the 
time of the digestive process ? 

CHAPTER VII. 

59. What is the first work of the stomach in digestion ? 

60. What is the effect of drink taken with food ? What suggestion 
is offered to persons who have weak stomachs? 

61. What is the proper moisture for food 1 

62. Will the stomach act more easily on a large or on a small quan¬ 
tity of food ? Is the quantity of nutriment always in proportion to the 
bulk of food ? 

63. With what should concentrated food be mixed? What is the 
practice of some rude northern tribes ? 

64. Is the nature of the food a matter of much importance ? 

65. 66, 67. Give the illustrations. 

CHAPTER VIII. 

68. - What is chyme? When does the food become chyme? Into 
what organ does the chyme pass from the stomach ? 

69. What coats compose the alimentary canal ? 

70. How does the mucous membrane of the alimentary canal differ 
from that of the stomach? What are its structure and offices? 

71. What are the lacteal absorbents ? How is the thoracic lacteal 
duct composed ? What the lacteal system ? What is its object? 

72. How are the different parts of the chyme disposed of? 

73. What occurs in the duodenum ? What is chyle? 

74. How is this separation effected ? 

75. On what does the proportion of chyle depend? What are the 
remote effects of imperfect mastication? 

76. By what means is the chyle conveyed from the alimentary canal 
to the blood ? 

77. Into what stages is the process of digestion divided ? How 
should each stage be performed ? 

77, 78. What other organs are connected with digestion? 

34* 


402 


QUESTIONS ON 


CHAPTER IX. 

79. How much do we know of the digestive process'? 

80. How far does the agency of man go in this process'? 

81. When are we unconscious of the process in the stomach ? When 
do we become conscious of it? 

82. What sensations accompany healthy digestion? 

83. At what stage of digestion does man’s agency cease, and when 
does nature take care of it ? What guide is needed ? 

84. What incorrect suppositions are mentioned ? Does hunger return 
as soon as the stomach is empty ? 

85. What creates a desire for food? What forms of disease prove 
this ? 

86. Where is the sensation of appetite ? What may result from a 
diseased state of the nerves of the stomach ? 

87. Can we need food without being conscious of it ? 

88. 89. Give the illustrations. 

CHAPTER X. 

90. How is the appetite affected by various bodily and mental states ? 

91. What does hunger indicate ? How do the wants of the body vary 
in a healthy state of the system ? 

92. Of what is appetite the usual sign? Should we eat when we 
are not hungry ? 

93. When does the desire for food fail to give evidence of digestive 
power ? 

94. What distinction exists between appetite and taste ? 

95. 96, 97. Relate some remarkable instances of absence of appe¬ 
tite under disease, or excitement. 

CHAPTER XI. 

98, 99. Relate some instances of extraordinary appetite for food ? 

100, 101. What causes may produce this extraordinary appetite? 

102. When is a new supply of nutriment needed? 

103. On what does the interval between the hours of eating depend ? 

104. How may the appetite be trained to return at regular intervals ? 

105. 106. Give some illustrations of the accommodating power of the 
stomach ? 

107. Will the stomach bear sudden changes in the time of eating ? 

108. Give an illustration. 

109. What are the effects of irregular hours of eating ? 

110. What, in general, are proper intervals of eating? 

CHAPTER XII. 

111. Why may the interval between the evening and morning meals 
be longer than others ? Why breakfast soon after rising ? 

112. What is recommended when the morning meal is late? 

113. When does the body sustain labor and exposure best? 

114. What advice is given in section 114 ? 


jarvis’s practical pyhsiology. 403 

115. Who especially should take early morning refreshment? 

116. What usages have prevailed in regard to the time of eating 
dinner ? 

117. What faulty custom is mentioned ? The common remedy ? 

118. Illustrate. 

119. Who may properly take a forenoon lunch ? 

120. How many daily meals are needed ? When may supper be 
omitted ? 

121. How long before sleeping should supper be eaten ? Why? 

122. What custom meets the wants of the body? What are the 
effects of more frequent meals ? 

CHAPTER XIII. 

123. Can the quantity of food be fixed by a uniform rule ? 

124. What is the rule in the British navy? In the army of the 
United States? What the rule for emigrant passengers? 

125. On what does the proper quantity depend ? Do corpulency 
and leanness depend on the quantity of food ? 

126. What illustration is given? 

127. How does occupation affect the quantity of food? 

128. What variation in diet should the same individual make ? 

129. What change of diet does change of occupation require ? 

130. What are the consequences of neglecting this change in the 
quantity of food ? 

131. State facts which have occurred at Cambridge. 

132. Why do growing persons require more food than adults? Why 
convalescents more than the healthy? 

CHAPTER XIV. 

133. What has been shown in sections 93, 94. 

134. How long may we safely eat ? 

135. Why should we eat slowly, and masticate thoroughly ? 

136. What would be a monitor of health, and preventive of disease 
connected with eating ? 

137. Who will not err in his diet? 

138. What sensations come from eating enough ? What from eat¬ 
ing too much ? 

3 39. Do evil consequences always follow excess of eating? 

140. Why is it not economy of time to eat hastily ? 

141. Illustrate. 

142. What habits often prevail in hotels and steamboats? 

CHAPTER XV. 

143. What is one proof of Divine benevolence and wisdom? What 
two principles are to be observed ? 

144 . What abuse may come from the pleasure of eating ? 

144, 145. Illustrate, and specify a difference. 

146. What is a common error in regard to eating ? 

147. What properties of food do most persons know ? Of what are 
they ignorant ? 


404 


QUESTIONS ON 


148. What usages of the table are injurious? 

149. What rites of hospitality violate the laws of digestion ? 

150. How are children often improperly indulged? 

151. Is such indulgence confined to children ? 

152. What are the consequences of these indulgences of appetite? 

153. What are the effects of deficient or bad food? 

154. Give illustration. 

CHAPTER XVI. 

155. What happens when some one organ, or portion of the body is 
in action ? 

156. Why should other organs rest while the digestive organs are 
active ? 

157. What comes from attempting the vigorous action of two parts 
of the body at the same time ? 

158. What kind of mental action interferes with digestion? What 
kind does not? 

159. Relate experiments on bounds. 

160. What kind of exercise is compatible with the digestive process ? 

161. What is the effect of exercising any of the organs violently? 

162. What is the effect on mental action? 

163. What is fatigue ? What is the process of rest ? 

164. Why is a short interval of repose needed between hard labor 
and eating ? 

165. State illustrations. 

CHAPTER XVII. 

166. What conditions are recommended during the time of eating? 

167. What should be avoided during the eating hour ? 

168. What is lost by disregarding the laws of digestion? 

169. How is dyspepsia produced ? 

CHAPTER XVIII. 

170. In determining what kind of food should be eaten, what pre¬ 
liminary questions are important? 

171. What question is still discussed? 

172. What examples do both parties find? 

173. Are there any advocates for an exclusively flesh diet? 

174. What is the general belief in regard to diet? Why? 

175. How do different kinds of food differ in their effect on the body ? 

176. What influence has climate on digestion? What is the food 
in the polar regions ? 

177. What in tropical? What usually in temperate regions? 

CHAPTER XIX. 

178. What differences in the temperaments of men ? 

179. What are marks of a lymphatic temperament? What food 
suits it? 


Jarvis’s practical physiology. 405 

180. How is the nervous temperament distinguished? What food 
suits it? What does not? 

181. What accompanies the sanguine temperament? What food is 
injurious ? 

182. How is the^bilious temperament distinguished ? 

183. What examples? What food is proper for it? 

184. What may we observe among our associates ? 

185. What is the consequence of disregarding temperament in the 
regulation of diet? 


CHAPTER XX. 

186. How does childhood differ from old age? 

187. What modification of diet does this difference require ? 

188. How should the habits of an individual modify diet? 

189. What relation has diet to employment? 

190. What is the consequence of neglecting this law? 

191. What does a change from light to severe labor require? 

CHAPTER XXI. 

192. In all kinds of food what two things are to be considered ? Are 
they identical? 

193. Who especially should make this distinction? Why? 

194. What are the natural effects of stimulation? Illustrate. 

195. Why are condiments and stimulants injurious to a healthy sto¬ 
mach ? 

196. What is the effect of alcohol? 

197. How do all stimulants affect the natural sensibility of the tongue 
and mouth ? 

198. Can the original sensibility be recovered? What has Dr. Kit¬ 
chener remarked ? 

199..What do we learn from this examination? 

200. What must every individual do ? 

201. Why cannot a dietetic code be framed suited to all men? 


PART II. 

CIRCULATION OF THE BLOOD AND NUTRITION. 
CHAPTER I. 


202. What becomes of the chyle? 

203. What is the apparatus of the circulation of the blood ? 

204. Describe the heart. 


406 


QUESTIONS ON 


205. How is the heart situated? What is its beating ? 

206. How is the heart divided ? 

207. What are the other divisions of the heart? 

208. What are the valves ? How do they act? 

209. What are the sets of blood vessels ? What relations have they 
to the heart? The body ? 

210. Describe the arteries. 

211. What is the aorta ? What its divisions ? 

212. Describe the subclavian arteries. 

213. Describe the arteries of the neck, head, and face. 

214. What are the inguinal arteries? the femoral? How are the 
arteries finally distributed ? 


CHAPTER II. 

215. What are the veins? 

216. What is the vena cava? What are its offices? 

217. What are the large branches of the veins? 

218. How are the veins finally distributed ? 

219. How are the arteries or veins arranged in respect to each other? 

220. What is the capillary system? 

221. What is the general circulation? 

222. Where are the arteries situated ? Why ? When is pulsation 
felt? 

223. Where are the veins situated? Why? 

224. How does the blood pass from the left to the right side of the 
heart? How from the right to the left? 

225. Describe the pulmonary arteries. The pulmonary veins. 

226. Describe the double circulation. 


CHAPTER III. 

227. By what force is the blood conveyed through the arteries ? 

228. How and upon what does the heart act ? 

229. What prevents the blood from flowing backwards? 

230. How are the arteries distributed ? What produces their beat¬ 
ing ? 

231. How is blood moved through the arteries? 

232. How much blood in a man of average size ? In what time 
does it all circulate through the system? 

233. What circumstances affect the rate of circulation ? 

234. Whose pulsations are strong? Whose feeble? Why? 

235. How do mental states affect the circulation ? 

236. Is the expansion of the arteries the same in all parts of the 
body ? 

237. How may we affect the circulation? 


jarvis’s practical physiology. 407 

CHAPTER IV. 

238. What materials of the body are obtained from the blood ? 

239. What elementary substances are found in the blood ? 

240. Are all these elements found in every texture of the body ? 

241. At what stage is the blood changed to flesh? 

242. Which makes the largest demand on the blood, growth or 
change of particles ? 

243. How are the new atoms of flesh disposed of? 

244. What is the office of absorbents ? 

245. Give Dr. Johnson’s description. 

CHAPTER V. 

246. Do the particles that compose our bodies remain the same ? 

247. How can the atoms change, without a change of the body? 
Ill ustrate. 

248. What experiments have been tried on pigs ? What result? 

249. How is this fact explained? 

250. During what part of life is the work of the arteries and absor¬ 
bents equal ? 

251. When does nutrition predominate? When absorption ? 

252. What is the effect of all exercise on nutrition and absorption? 

253. What law is a physical one, as well as moral ? 

254. How may the relative activity of destruction and. creation be 
disturbed ? 

255. How are wens and other fleshy tumours produced ? How scat¬ 
tered ? 

CHAPTER VI. 

256. Is the work of nutrition and absorption equally rapid at all pe¬ 
riods ? 

257. Whose flesh is ever young ? Whose ever old ? 

258. Where does our knowledge of nutrition end? 

259. What elements do the nutritive organs select to form fat? hair ? 
muscle ? 

260. Do the nutritive organs ever misplace a particle ? 

261. How does arterial blood differ from venous? 

262. By what means is the venous blood renovated? 

PART III. 

RESPIRATION. 

CHAPTER I. 

263. How are the wasted particles of the body disposed of? 

264. Of what parts does the venous blood consist? Why would not 
these nourish the body ? To what process must they be submitted ? 


408 


QUESTIONS ON 


265, 266. How are the lungs situated and protected ? 

267. Describe the spine. 268. Breast-bone. 269. Ribs. 270. Their 
position. 


CHAPTER II. 

271. What provision for moving the ribs ? 

272. What motion of the ribs expends the chest? 

273. 274. What is the diaphragm, and its office in respiration ? 

275. Describe the process of inspiration. 276. Of expiration. 

277. Explain fig. VI. 

CHAPTER III. 

278. What is the relative position of the heart and lungs? What 
the substance of the lungs ? 

279. Describe the air-tubes; the blood-vessels of the lungs? 

280. What is the windpipe ? 

281. What is the organ of voice ? Its diseases? 

282. How is the windpipe divided? What are the air-cells? 

283. How are the air-vessels lined ? What is coughing ? 

284. How may sensibility be impaired? 

285. How are the minute arteries separated from the air-cells ? 

286. 287. What two operations constitute respiration? 

288. Name the organs employed in respiration. 

CHAPTER IV 

289. What elements of waste matter are separated from the blood? 
How ? 

290. Into what does carbon enter and compose a part? 

291. What are the constituents of the atmosphere? 

292. What is oxygen, and what are its combinations? 

293. What is nitrogen and some of its combinations ? 

294. What new compounds are formed in the lungs? 

295. What is carbonic acid ? Where found ? Its properties ? 

296. 297. What interchange takes place between the air and blood ? 

CHAPTER V. 

298. In what state does the blood enter the lungs ? In what state 
does it leave them ? 

299. Why do the veins, and the flushed cheek differ in color? 

300. What is the effect of respiring the same air several times? 
How much does our respiration change it? 

301. Give Davy’s experiment. 

302. What is the point of saturation ? 

303. How may it be shown that water comes from the lungs? 

304. What other matters are carried off by the lungs? 


409 


jarvis’s practical physiology. 

CHAPTER VI. 

305. What part of the oxygen of the air does one respiration con¬ 
sume ? 

306. Will a second respiration, and a third, consume each another 
fourth ? 

307. Give an illustration. 

308. Will any other proportion of oxygen, than that which is in pure 
air answer ? 

309. What besides the loss of oxygen unfits the air for a second res¬ 
piration? 

310. What is the limit of the capacity of air to remove offending 
matter from the lungs ? 

• 311, 312. Illustrate. 

313. What is removed from the lungs besides carbon? 

314. In what three ways is air vitiated? 

CHAPTER VII. 

315. How does temperature of the air affect the removal of waste? 

316. What sensations are experienced in warm weather? Why? 

317. How does mountain air affect breathing? 

318. What impurities in some mines? What their effect? 

319. Does the state of the system affect the removal of waste? 

320. How do diseases of the lungs impair respiration? 

321. What occurs in lung fever and some other diseases? 

322. What effect have mental states? 

CHAPTER VIII. 

323. What does respiration imply in regard to the chest ? 

324. What organs are passive in respiration ? 

325. 326. What apparatus is active, and how does it act ? 

327, 328. How may the motions of the ribs be impeded? 

329, 330, 331. How may the motions of the diaphragm be impeded ? 

CHAPTER IX. 

332. What is the natural principle of beauty ? What the ideal ? 

333. What is the relation of the chest to the body ? 

334. What principle of utility is to be considered in the size of the 
chest? 

335. What is the real standard of beauty of the chest and waist ? 

336. When do we find the waist of natural shape ? What is it? 

337. W'hat is the effect of close and small dresses on the chest? 

338. What upon respiration ? 

339. 340. How does pressure affect the bony frame ? The ribs ? 

CHAPTER X. 

341. What disorders may impede the action of the diaphragm? 

342. What is the average number of respirations in a minute ? 

35 


410 


QUESTIONS ON 


343. What is the average capacity of a man's lungs, when not ex¬ 
panded ? How much air is received at each inspiration ? 

344, 345. Does the quantity of air inspired correspond to the amount 
of waste to be removed ? 

346. What are nearly the proportions, of blood, of air, and of waste ? 

CHAPTER XI. 

347, 348. How much air is unfitted for respiration in a minute by 
the loss of oxygen ? What per cent, of carbonic acid gas unfits air for 
respiration ? How much does one person unfit in this proportion in 
one minute ? 

349. How much watery vapor will air at 32° contain ? How much 
at 65° ? at 70° ? 

350. When is this vapor condensed ? When frozen ? 

351. How much air will the vapor from the lungs saturate in a 
minute? 

352. What other source of moisture ? 

353. What is the average amount of insensible perspiration in a 
minute ? 

354. In what three ways is air unfitted for respiration? 

CHAPTER XII. 

355. How much fresh air ought to be supplied to each person per 
minute ? 

356. 357. What is neglected in dwellings and public rooms ? What 
partially remedies the neglect? 

358, 359. Mention a deficiency in sitting rooms ; in sleeping rooms. 

360. Deficiencies in public boarding houses, &c. 

361, 362,363. What other places are still more crowded ? 

CHAPTER XIII. 

364. How large a workshop is thought sufficient for six or eight men ? 

365, 366. What other places are badly ventilated? 

367. What facts are mentioned respecting churches? 

368. And halls? 

369. What facts, respecting school-houses? 

370. To what does habit reconcile us? 

371. Do persons entering a crowded room, and those living in it, have 
the same sensations? 

372. What fails to be accomplished in such cases? 

373. For what do well-arranged means of ventilation provide? 

CHAPTER XIV. 

374. What correspondence between respiration and vital energy? 

375. What illustration do hybernating animals afford? 

376. What animals are most active? What most sluggish ? 

377. In the same class, who have a lower life than others? 

378. How does consumption waste the flesh and strength? 

379. 380. What is a necessary result of imperfect respiration ? 

381. Why does sleep sometimes fail to refresh? 382. Illustrate. 


411 


jarvis’s practical physiology. 

CHAPTER XV. 

383. What effect has corrupted air on a crowded audience ? 

384. What effect has an ill-ventilated school-room on the children? 

385. What occurred in the Black-hole of Calcutta ? What is the dif¬ 
ference between this result and the faintness of a crowded room ? 

386. What effect has pure carbonic acid gas ? 

387. What is a common source of danger from carbonic acid gas ? 

388. How does drowning produce death ? 

389. What are some more remote effects of bad air? 

390. Why are females more susceptible of consumption than males ? 

CHAPTER XVI. 

391. How does the privation of air affect different animals? 

392. What power can man acquire by long practice ? 

393. What necessity is imposed on all animals ? 

394. 395. Is there any natural deficiency of air? 

396. What reciprocal offices do animals and vegetables perform ? 

397. When do vegetables consume carbonic acid ? When give it 
out? 

398. When are house-plants salutary ? When injurious ? 

PART IV. 

ANIMAL HEAT. 

CHAPTER I. 

399. What is the temperature of most animals compared with that 

of the surrounding medium ? 400,401. What illustrations ? 

402. What were the experiments of Sir Charles Blagden ? 

403. What tendency is almost universal ? 404. Illustrate. 

405. What exception to this tendency ? 

406. What effects would follow, if living bodies could not retain a 
uniform temperature ? 

CHAPTER II. 

407. How is the heat of the living body affected by cold bodies? 

408. How does the law of heat among dead substances differ from 
this ? 

409. What is the origin of the heat in living bodies? 

410. Into what classes are animals divided in relation to heat? 

411. From what difference of structure does this difference of tem¬ 
perature arise ? 

412. Does the same distinction occur among the inhabitants of the 
sea ? 

413. What conditions are necessary to maintain this internal heat? 


412 


QUESTIONS ON 


CHAPTER III. 

414. With what process is internal heat connected ? 

415. What do we understand by the term latent heat? 

416. What is given us as a general law of matter? 

417. What is the difference between sensible and specific heat ? 

418. How does combustion illustrate this distinction ? 

419. Apply these principles to explain animal heat. 

420. What was once generally believed? 

421. What is the process now generally maintained ? 

CHAPTER IV. 

422. How does exercise increase animal heat? 

423. How does impeded circulation affect the temperature ? 

424. How is this internal combustion maintained ? How impeded ? 

425. What hindrances are enumerated? 

426. Why do persons in a crowded room grow cold? 

427. Who need most external protection from cold, and why? 

428. What is needed to maintain this internal combustion besides 
air ? How is it supplied ? 

429. Who can best resist external cold? 

430. Which protects from cold best, alcohol or food ? 

431. Which warms most, flesh or bread? What necessity has na¬ 
ture met and supplied ? 


CHAPTER V. 

432. What other influences affect the supply of heat? 

433. How do different states of the system modify the quantity of 
heat ? 

434. What lessens the production of heat ? 

435. What difference at different periods of life ? 

436. How does sleep affect the power of producing heat ? 

437. On what does the amount of heat in combustion depend ? 

438. How much heat is generated in the body in a day? 

439. What prevents an increase of temperature in the body ? 

440. How does heat escape from the body? 

441. What active power does the skin exert? In what way does 
perspiration cool the body? 

442. How do Blagden’s experiments illustrate this principle ? 

443. What beautiful adaptation is mentioned ? 

444. What is the winter constitution ? The summer constitution ? 

445. What were the experiments of Dr. Edwards ? 

446. Why is the transition from the cold of winter to the heat of 
summer unattended with suffering ? 

447. Who especially need the protection of thick clothing in win- 


413 


jarvis’s practical physiology. 


PART V. 

SKIN. 

CHAPTER I. 

448. What protects the organs of life from external agencies? 

449. Describe the cuticle. 450. Is it subject to change? 

451. When does it become thick and tough? 

452. Will every kind of friction produce this effect? 

453. What is the effect of friction gradually applied ? 

454. To what extent may the outer skin be made thick and tough ? 

455. How does new and coarse work affect the hands ? 

456. How are corns produced ? 

CHAPTER II. 

457. What protection does the cuticle afford? 

458. What other parts grow out of the cuticle? 

459. Describe the nail. 

460. What is the structure of the hair? 

461. How is the scarf-skin kept fresh and new ? 

462. Where is the seat of color? What is the rete mucosum? 

463. What produces various hues in some animals? 

464. Describe the true skin? 

465. When is the surface florid? What may make it more so? 
Less so? 

466. What sense and what degree of sensibility are in the skin ? 

467. What is directly under the skin ? Where thick? Where thin? 

CHAPTER III. 

468. In what form does the waste of the body escape through the 
skin? In what quantity ? What was Sanetorius’s experiment? 

469. At what results did Seguin arrive ? 

470. How can this insensible perspiration be made manifest? 

471. What is sensible perspiration? Which is constant? Which 
greatest in the whole amount? 

472. 473, 474. Relate the experiments at the Phoenix gas works. 

475. How is the weight of the body kept uniform ? 

476. What is the average amount of cutaneous exhalations ? What 
produce variations? 

CHAPTER IV. 

477. What external circumstances modify the amount of perspira¬ 
tion ? 

478. What is the effect of the atmosphere saturated with moisture ? 

479. Describe the minute structure of the perspiratory organs. 

35* 


414 


QUESTIONS ON 


480. Do all animals possess the perspiratory apparatus ? 

481. What provision for keeping the skin soft and smooth? 

482. What properties has this oily secretion ? 

483. What will render the skin stiff and hard? 

484. What kind of clothing is injurious? and why ? 

485. What kinds of hats are too close? 

CHAPTER V. 

486. What connection exists between the skin and the internal or¬ 
gans of the body ? 

487. What facts illustrate this connection ? 

488. How are the lungs and skin related ? What are their sympa¬ 
thies ? 

489. What relations exist between the skin and the digestive organs ? 

490. 491. What internal organ is most liable to suffer when the cu¬ 
taneous circulation is disturbed ? 

492. What may always be inferred, when the skin is dry ? 

CHAPTER VI. 

493. When does the skin act as an absorbent ? 494. Give illustration. 

495. State the case of absorption in a hot bath, and that of Ann Moore. 

496. What other substances may be absorbed ? 

497. 498. What facts prove cutaneous absorption? 

499. At what times is the absorbing power most active ? 

500. What stimulates the cutaneous absorbents ? 

CHAPTER VII. 

501. Is the sense of touch uniform over the whole body? 

502. When is cutaneous sensibility most acute ? In what persons ? 

503. On what does the facility of cutaneous sensation depend ? 

504. What can education do for the sense of touch ? 

505. How is the loss of one sense compensated? 

506. What illustrations do the blind and some others furnish ? 

507. What blunt the sensibility of the skin? 


CHAPTER VIII. 




508. How does the skin prevent the effects of heat and cold? 

509. What tendency is constant? What its effect? 

510. Why is perspiration a cooling process? 

511. How do different states of the air affect its cooling powers? 

512. In what state does the skin perform its functions well? 

513. How do some states of disease affect the skin? 

514. Can we measure temperature correctly by touch? 

515. What illustration may two travellers furnish? 

516. What bodily and mental states favor, and what impede the 
healthy action of the skin ? 


jaryis’s practical physiology. 415 

CHAPTER IX. 

517. What three offices does the skin perform? 

518. Do the functions of the skin require the aid of clothing? 

519. What is the practical view of the case? 

520. Do all parts of the skin protect equally well? 

521. What illustration is drawn from the dress of the two sexes ? 

522. What from the Indian? From the Highlander? 

523. 524, 525. Give the facts and the conclusions to which they lead. 

526. What practical suggestions are given ? 

527. What effects do habits of dress in different periods of life pro¬ 
duce ? 

CHAPTER X. 

528. 529, 530. What, besides habit, should influence the amount of 
clothing ? 

531. Can a general rule be given? 532. What general directions? 

533. What are the effects of too little clothing ? 

534. What power comes from habitual exposure ? 

535. Can all persons acquire this power suddenly ? 

536. Why do infancy and old age require more clothing than the 
middle period of life? 

537. How can even the feeble gain their power of endurance? 

CHAPTER XI. 

538. What qualities should clothing possess ? 

539. Why are loose garments warmer than tight? 

540. What are the objections to inner garments of linen? 

541. What are the good qualities of cotton? 

542. What qualities has silk for inner garments ? 

543. What qualities recommend woollen garments? What bad ef¬ 
fects on some? 

544. Against what should the skin be guarded? What is the best 
protection ? 


CHAPTER XII. 

545. What fact proves the good effects of flannel ? 

546. What other measures were used for the health of seamen ? 

547. 548, 549. What do inner garments retain ? 

550, 551. What changes should be practised ? 

552. How should beds and bed-clothes be treated ? 

553. What objectionable practice prevails on board canal-boats ? 

554. What injurious necessity exists in some dwellings ? 

CHAPTER XIII. 

555. What change of the cuticle goes on constantly? 

556. What effect of the warm bath is mentioned ? 

557. What neglect are many persons guilty of? 


416 


QUESTIONS ON 


558. What difference between their skins and that of those who 
bathe ? 

559. What daily practice does perfect health require ? Is water 
alone sufficient ? 

560. What custom has prevailed in some nations ? 

561. In what are the English and Americans surpassed by some 
other nations? 

562. Describe different kinds of baths. 

CHAPTER XIV. 

563. What bath is suitable in good health ? 

564. What maybe easily used instead of a plunge bath? 

565. What are a proper time and manner of taking the cold bath ? 

566. Is the time required for the bath lost time ? 

567. Who may not safely use the cold bath ? 

568. What is occasionally necessary? 

CHAPTER XV. 

569. What are the good effects of cold bathing? 

570. What confirmation does Dr. A. Combe give ? 

571. What is recommended to the weakly? 

572. What condition of the stomach should be regarded ? 

573. What is the best time for the bath ? 

574. What common notion is erroneous ? 575. Give an illustration. 

576. To what else may the same principles be applied ? 

CHAPTER XVI. 

577. What effect has bathing on the nervous sensibility? Why is 
a burn on the skin often more dangerous than a deeper wound ? 

578. What neglect blunts the sensibility of the skin ? How does 
cleanliness increase it? 

579. State the case of Laura Bridgman. 

580. What is the practice of Esquirol ? 

581. What has been shown in regard to the structure and offices of 
the skin ? 

582. What duties belong to every human being? 


PART VI. 


BONES, MUSCLES, EXERCISE, AND REST. 


CHAPTER I. 


583. What is the structure of the bones ? When are they strong ? 

584, 585. What is the condition of the bones at different periods of 
life ? 



417 


jarvis’s practical physiology. 

586. With what organs are the bones supplied? 

587. How are broken bones re-united? 

588. What shows the process of absorption and deposition? 

589. What effect has exercise on the bones ? 

590. What stunts the growth ? How may the bones of childhood 
be distorted ? What injury is sometimes done in schools ? 

591. What causes the rickets? Who are exposed to this disease? 

592. What is the internal structure of the bones ? 

CHAPTER II. 

593. How many bones in the human frame ? What their shapes ? 

594. Describe the principal parts of the bony frame. The skull. 

595. Describe the chest; the spine; a vertebra. 

596. How are the vertebrae distributed? 

597. What substance between the vertebrae? How does it aid in 
bending the spine ? Why is a man shorter at night than in the morn¬ 
ing? 

598. What is the shape of the spine ? 

599. Describe the pelvis. 

CHAPTER III. 

600. Describe the upper extremities: shoulder blade : collar bone : 
arm : wrist: hand. 

601. Describe the lower extremity: the foot. 

602. Describe composition and form of the foot. 

603. How may the benefit of the arch be shown ? 

604. How do we avoid a jar in jumping from an elevation ? 

605. What is the natural shape of the foot? What the artificial? 

CHAPTER IV. 

606. What office do the joints perform? What are the different 
kinds of joints ? 

607. Describe the hip joint. 

608. Describe the upper joints of the neck. 

609. 610. What contrivance to prevent jars and friction? 

611. What keeps the joints from wearing out? How are they kept 
moist? 

612. How are the bones held together? What is the synovial 
membrane ? 

613. What is a sprain ? 

614. How are the bones dislocated ? 

CHAPTER V. 

615. Describe the muscles. What is their office ? 

616. What is their power ? What is their action? 

617. How are they arranged? 


418 


QUESTIONS ON 


618. Describe the muscles that lift the shoulder; that bend the elbow; 
that draw the arm forward ; that bend the wrist. What is the tailor’s 
r^uscle ? What muscles bend the hip joint? What muscles straight¬ 
en the leg? 

619. Describe the Trapezium muscle. Describe the muscle that 
straightens the elbow ; that straightens the hip; that bends the knee ; 
that straightens the ancle. 

620. Describe the muscles that draw the shoulder forward; that roll 
the thigh outward. 

CHAPTER VI. 

621. What are the shapes of the muscles ? 

622. How does the diaphragm act ? The heart ? The oesophagus ? 

623. What is done by the muscles ? 

624. How are the muscles attached ? Describe some of the muscles 
on the face ? 

625. How are the muscles placed in regard to the bones? 

626. What occurs in the muscles when they act ? How can you 
feel their action ? 

627. When can the action of certain flat muscles be perceived ? 

628. How many sets of muscles has each hinge joint? What is the 
office of each set ? 

629. How can you perceive the alternate working of the muscles 
that move the fingers ? 

630. How is the variety of motions produced in the ball and socket 
joints, and in some others ? 

CHAPTER VII. 

631. What muscles act at disadvantage ? 632. Illustrate in fore-arm. 

633. Why is this loss of power made ? How is it provided for ? 

634. Give another illustration. 

635. Specify instances of rapid muscular motion. 

636. Specify instances of action by a concert of muscles. 

637. What power do performers on the piano-forte acquire? 

638. What precision does a skilful violinist acquire ? 

639. What illustration may be drawn from the act of writing? 

640. What does this control over muscular action enable men to do ? 
Give an illustration. 

CHAPTER VIII. 

641. To what is the strength of muscles generally proportioned? 
What exceptions ? 

642. How does the strength of man compare with that of a flea? 

643. To what does muscular power correspond ? 

644. For what purpose is muscular power given? 

645. How do the muscles.of the active and inactive differ? 

646. 647. Give the first illustration. Second. Third. 

648. What employments develop the muscles best? Why? 

649. What employments develop some muscles disproportionately? 
Why ? How ; s this shown in other animals ? in birds ? 


419 


jarvis’s practical physiology. 


CHAPTER IX. 

650. Why are some persons strong in one part and weak in another 1 

651. Give illustration. 

652. How are the size and strength of the muscles preserved ? 

653. Illustrate. 

654. What collateral advantages result from muscular exercise? 

655. What connection has digestion with exercise ? 

656. How does exercise aid the circulation ? 657. How respiration ? 

658. How does exercise increase animal heat? 

CHAPTER X. 

659. How does a muscle gain size and strength by exercise ? 

660. What other benefit of exercise is mentioned ? 

661. What difficulties may be removed by exercise 1 662. Give the 

history of the robust boy ? 

663. How is each one to determine his proper degree of exercise ? 

664. What results indicate too much action? What result indicates 
enough ? 

665. What is said of the permanence of muscular action? 

CHAPTER XI. 

666. 667, 668. How should the feeble begin to exercise ? Give aa 
illustration. 

669. When do debilitated students, &c., derive no benefit from 
labor ? 

670. What is recommended to invalids going to sea for health ? 

671. Why have not gymnastic exercises produced the expected 
result? 


CHAPTER XII. 

672. What kind of exercise is best? 673. How should we walk? 
674. What exercises are allowed to boys? 675. How are girls re¬ 
stricted ? 

676. What custom preyails among English women ? 

677. What employments may be combined with walking? 

678. In what circumstances is dancing a good exercise ? 

679. 680, 681. Give the suggestions relating to the time of taking 
exercise. 

CHAPTER XIII. 

682. Where should exercise be taken? Why? 

683. What kind of weather may prevent exercise abroad? 

684. Are any exempted from the need of exercise ? 

685. 686. What, besides the quantity of exercise, demands attention ? 

687. Are the consequences of neglect sudden ? or remote ? Are they 
the less certain ? 

688. What laws are established ? 


420 


QUESTIONS ON 


CHAPTER XIV. 

689. Is the exercise which health requires, the limit of muscular 
power ? 

690. What questions are important for the laborer ? 

691. How can the laborer know he has overworked? How long 
may he increase his exertions ? 

692. How can he maintain the fulness of his strength ? 

693. Has man an indefinite power of endurance? 

694. How is premature old age sometimes induced ? 

695. What is a common effect of overworking ? Illustrate. 

696. Among what class is the length of life shortest? 

697. May not other circumstances account for the shorter life of the 
day-laborer and sailor? 

CHAPTER XV. 

698. Does excessive labor for a short period produce the same kind 
of result? 

699. What permanent injury often results? Illustrate. 

700. Who suffers most from great exertion ? 

701. When does a man acquire full strength? What is the order 
of development of power ? 

CHAPTER XVI. 

702. Why does labor require healthy organs of digestion and nutri¬ 
tion ? 

703. What kind of food does labor require ? Why ? 

704. What kind of food should a laboring man eat? Why ? 

705. Can a man labor well whose skin and lungs are not in a healthy 
condition? Why? 

706. How do diseases of the heart unfit for labor? 

707. How do the state and health of the brain and mind affect the 
ability to labor ? 

708. 709. What is the proper state of the brain and mind while 
taking exercise ? 

• 

CHAPTER XVII. 

710. What motive does labor for profit require? 

711. What are the effects of hope and despair on labor? 

712. What of confidence, and of doubt? 

713. What is the effect of cheerfulness and of melancholy? 

714. What is the effect of alcoholic liquors? 

CHAPTER XVIII. 

715. What is the natural form of the spine ? How is the head held ? 

716. Describe the muscles of the back? 

717. How does a curvature of the spine affect the muscles of the 
back? 


421 


jarvis’s practical physiology. 

718. What is said of the strength of the back? What illustration? 

719. What is the best position of the spine for burdens on the head ? 

720. How is the head carried most easily? Explain. 

721. What is said of the centre of gravity in carrying burdens? 
Give illustrations. 

722. What farther illustrations ? 

723 Explain this farther. 

724. What is said of the grace of this attitude ? 

CHAPTER XIX. 

725. What is the best attitude for walking? Why? 

726. What for labor? What illustration? 

727. What other persons act best in this position? 

728. How is the lateral curvature of the spine induced ? 

729. How is the forward curvature produced ? Who are liable to it? 

730. Who are exposed to this curvature? How? 

731. How is the spine affected by the position of persons writing? 
or reading ? 

732. What is Dr. Warrens’ opinion? 

733. Why are boys less subject to curved spine than girls? 

734. How are the lungs affected by curved spine? 

735. 736. How is the spinal cord? 

CHAPTER XX. 

737. What law of nature is almost universal? 

738. What disadvantages has night labor? Illustrate. 

739. What is the experience of milkmen and others who devote a 
part of the night to their business ? 

CHAPTER XXI. 

740. What natural indication does man need to follow ? 

741. Can the quantity of sleep be fixed by a general rule? 

742. What shows night to be the season of sleep? 

743. W T hat is the uniform effect of loss of sleep ? 

744. Why does sleep require an increase of clothing? 

745. What are the conditions necessary for refreshing sleep ? 

746. Does the digestive process go on well in sleep? 

PART VII. 

BRAIN AND NERVOUS SYSTEM. 

CHAPTER I. 

747. Describe the brain. 

748. Into what portions is the brain divided ? 

749. What are the offices of the membranes which divide the brain? 

750. What is the spinal cord, and its position? 

36 


422 


QUESTIONS ON 


751. How is every organ connected with the brain? 

752. What two kinds of nerves, and what their offices ? 

753. How is it shown that they perform separate offices ? 

754. How do these two kinds of nerves differ in their termination? 

CHAPTER II. 

755. What three things are necessary for sensation ? 

756. What happens when the foot is asleep ? 

757. How do the nerves pass from the brain to the trunk and ex¬ 
tremities ? 

758. How do injuries to the spine affect the nerves? 759, 760, 761. 
Give illustrations. 

762. What does the case of Mr. J. illustrate? 

CHAPTER III. 

763. Why does the brain refer sensations to the end of the nerves ? 

764. If the trunk of the nerve is irritated or injured, to what part is 
the impression referred ? 

765. Where is the seat of disease in the tic douloureux? 766. Il¬ 
lustrate by Miss W.’s case. 

767. Where do the nerves of special sense receive impressions? 
How can an impression like that of light be made on the brain, when 
the eye is closed ? 

768. What illustrations are derived from the sense of hearing, and 
of taste? 

769. What is the effect of exciting a nerve in any part of its course ? 

770. Illustrate. 

CHAPTER IV. 

771. What fact does the last section explain? 

772. How is muscular motion excited naturally? How artificially ? 
Illustrate. 

773. Where is sensation? What is its immediate cause? Where 
is a true sensation excited? Where a false one ? How do the cham¬ 
ber bells in a hotel illustrate true and false sensations ? 

774. What instances of false sensations are mentioned ? 

775. Is the communication through the nerves rapid? 

776. What organs are voluntary ? Why so called ? What are in¬ 
voluntary? Are these supplied with nerves? 

777. Do the voluntary organs ever act involuntarily ? State cases. 

778. What voluntary motions become apparently involuntary? 

779. Why do familiar motions exhaust less than others? Illustrate. 

780. On what does the power of every organ to act depend ? 

CHAPTER V. 

781. Why is the brain carefully guarded from injury? 

782. The brain is the seat of what? 

783. Is the brain sensitive ? Illustrate. 

784. What is the effect of pressure on the brain? 


423 


jarvis’s practical physiology. 


785. Relate a case recorded by Sir Astley Cooper. 

786. Is the brain subject to growth and decay? With what appara¬ 
tus is it furnished ? What part of the blood of the body does the brain 
receive ? 

787. What effect has the action of the brain on its blood-vessels? 

788. When does the brain require rest? 

789. What is the natural rest of the brain? What kind of sleep 
refreshes the brain most ? 

CHAPTER VI. 

790. What is the proper season for mental labor ? For mental re¬ 
pose? 

791. What do some students practise? With what effect? When 
has the brain naturally the greatest power for labdr ? 

792. What effect has proper exercise on the brain? What effect 
has excessive exercise ? 

793. What relation exists between the brain and other organs? 

794. What between the brain and heart? 795. Between the brain 
and lungs? 796. Between the brain and stomach? 797. Between 
the brain and muscles? 

798. How does alcohol affect muscles? 799. Is this permanent? 

800. Illustrate. 

801. Why is the drunkard, when sober, exposed to accidents ? 

CHAPTER VII. 

802. How does the mind communicate with the external world ? 

803. What fixes a limit to the action of the human mind ? 

804. What reciprocal influences are exerted by the brain and the 
mind ? 

805. Mention some specific influences. 

806. State the case of a child. 

807. What is the effect of indigestion and nausea ? 

808. How does excessive eating affect mental action? How does 
hunger ? 

809. How are the moral powers and affections influenced by the 
stomach ? Illustrate. 

810. What effects are ascribed to cheerfulness ? What to sorrow and 
care ? 

811. What feelings favor digestion? What feelings retard it? 

812. What connection has health with cheerfulness? 

CHAPTER VIII. 

813. What operations does the brain superintend? How far is it 
under our control? How far are we responsible for its action? 

814. When does the brain perform its offices well? When not 
well ? 

815. When can the brain superintend more than one operation at a 
time ? When only one ? 


424 


QUESTIONS ON 


816. When can the brain superintend only the involuntary opera¬ 
tions ? 

817. Explain this by the musician. 

818. In what conditions can the mind be concentrated on a subject? 

819. What faults in many school-rooms interrupt study? 

820. What further faults are mentioned? 

821. Why is fatigue incompatible with mental labor? 

CHAPTER IX. 

822. 823. How do moral feelings affect mental attention ? 

824. What illustration does the school-room furnish? 825. What 
other illustrations ? 

826. What seeming exceptions are mentioned ? 

827. How are they^reconciled with the general principle ? 

828. What do these disturbing influences require ? 

829. What motives for study may interrupt it? 830. Illustrate. 

831. What motives aid the mind in fixing attention on a subject ? 

CHAPTER X. 

832. What differences exist in the various faculties of the same per 
son ? Of different persons ? What is the cause of this difference ? 

833. How are the mental and moral powers strengthened ? What 
is the purpose of education ? In what order do the powers appear ? 

834. How is the child prepared for abstruse subjects ? 

835. What are some characteristics of childhood ? 

836. Can the mind be prematurely strengthened ? 

837. What is the effect of premature mental exertion ? 

838. What dependence among the organs ? Illustrate. 

839. Why does the health of students often fail ? 

840. Is mental effort compatible with health and long life ? 

CHAPTER XI. 

841. Are the several systems equally strong in the same person? 
How can this diversity be remedied ? 

842. How can mental irregularities be remedied ? What is often 
done at variance with the proper remedy? 

843. What will be the state of the faculties which are exercised? 
What of those not exercised ? 

844. What illustration is drawn from the mechanic arts? 

845. What is the effect of exclusive cultivation of some of the intel¬ 
lectual powers ? 

846. Does the same principle apply to the moral powers ? Illustrate. 

847. What facts show that any faculty can be strengthened at any 
time of life ? 

848. How does constant use affect the power of observation? 

849. Show how the same principle applies to the moral powers. 

850. What part of this work belongs to teaching? What part to 
practice ? 

851. How can true politeness be distinguished from the assumed? 


425 


Jarvis’s practical physiology. 


CHAPTER XII. 

852. Who are a man’s chosen associates ? Why ? 

853. Why are men unused to society often averse to it? What is 
the character of people long excluded from the world? 

854. How is the acquired strength of the mind to be preserved ? 

855. What constitutes completeness of character ? What are its ad¬ 
vantages ? 

856. What is mental concentration? 

857. What is one difference between a strong and a weak mind? 

858. On what does the progress of a student mainly depend ? 

859. Does the exercise of the brain afford pleasure ? 

860. To what degree must the brain be exercised, that it may do a 
full day’s work every day ? 

861. Is any thing gained by overworking the brain? Illustrate. 

862. Does a high mental excitement subside, as soon as the exertion 
ceases ? Illustrate. 

863. How should our business and studies be arranged? What is 
the fault of the actual arrangement ? 

CHAPTER XIII. 

864. What diversity is found in the digestive organs ? What is the 
effect of eating indigestible food ? 

865. How does the same rule apply to the mind ? 

866. How are some men affected by intense application to subjects 
out of their common course ? 

867. 868. How do the ills of the other organs affect the brain? 

869. How does great cold affect the brain? Great heat? 

870. What abuses may lead to insanity ? 871. Illustrate. 

CHAPTER XIY. 

872. What is the effect of misdirected education? 

873. What expectations may produce the same effect? 

874. What is the effect in some cases of religious anxiety? 

875. What is the tendency of natural, or artificial appetites, if in¬ 
dulged ? 

876. What may be the effect of irregular mental habits ? 

CHAPTER XV. 

877. What is day-dreaming ? 878. To what results does it lead ? 

879. What is the effect of strong emotions? Of fright? 880. Of 

uncontrolled passion ? 

881. How do physical stimulants affect the brain? 

882. Is insanity the uniform result of these causes? Between what 
extremes do they leave the mind ? 

883. To what extent is man responsible for mental health and 
strength? 

3b * 


426 


QUESTIONS ON 


CHAPTER XVI. 

884. Where is the eye placed ? 

885. What is the aqueous humor ? What the vitreous ? The crys¬ 
talline lens ? 

886. Describe the sclerotic coat; the cornea. 

887. 888. Describe the choroid coat; the retina. 

889. What are the parts of the eye, beginning in front? Describe 
the iris; the pupil, and its action. 

890. Describe the lids. 

891. Describe the apparatus for the tears. 

892. What happens sometimes to the lachrymal canals ? 

893. What sympathies has the lachrymal apparatus ? 

894. What move the eye? 

895. What is the cross-eye ? 

896. Describe the optic nerve. 

897. How is vision produced ? 

CHAPTER XVII. 

898. What is near-sightedness? How may it be avoided ? 

899. What is the state of the lens? What is the effect of concave 
spectacles ? How should they be worn ? 

900. What is the effect of single eye-glasses ? 

901. What is far-sightedness? 

902. What are some of the diseases of the eye ? 

903. How should the eye be treated for cleansing ? 

904. How is the eye affected by air ? 

905. Who have weakened vision? 

906. How are the eyes sometimes injured ? 

907. What is the effect of protracted use of the eyes ? 

CHAPTER XVIII. 

908. What does the organ of hearing include ? 

909. Describe the outer ear. 

910. What is the natural position of the ear? 

911. Should the ear be covered? 

912. Describe the external canal. 

913. Describenhe membrane of the tympanum. 

914. Describe the internal cavity. The Eustachian tube. What 
office does this tube fulfil ? 

915. 916. What are within the drum? 

917. What is the auditory nerve? 

918, 919. How is sound produced? What is necessary ? 

920. How do we know that air is necessary ? 

921. What is the effect of unsound ears ? 

922. What happens sometimes to the Eustachian tube ? 

923. 924, 925. What causes deafness ? 


ERRATA. 

Page 326, line 3,—for 'pink, read gray. 

te (( 4,—for gray or ashy , read white. 

“ “ 4,—for cineritious , read medullary . 















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jarvis’s practical physiology. 427 

926. Is this faculty always the same ? 

927. What is said of the ear for music? 

928. What is man’s responsibility in regard to his body? What is 
the consequence of violations of the law? 

929. What relations exist among the bodily, intellectual, and moral 
powers? 

930. What are the intentions of nature in regard to man ? Does he 
realize them? 

931. What is perfect health? 

932. What seems to be expected as the common lot of all? What 
causes a greater loss than prostrating sickness ? 

933. What is supposed to be the natural period of human life ? T 
this often attained? What is the average duration of life in Masst 
ohnsetts ? In Sweden? In Russia? Among different classes in En¬ 
gland ? 

934. To what conclusions do these facts lead us? 

935. Is this abridgment of life owing to natural defects? 

936. What are the most common causes of death? 

937. What proportion in Massachusetts died because the machinery 
of life was worn out? From what cause may the premature failure 
of one, or of all the organs arise ? 

938. How should strength be added ? How may a portion of it be 
expended? How may we err? 

939. What is meant by the term constitution? To what may it be 
compared ? 

940. How may vital power be expended ? When is a sufficiency 
of vital power produced ? 

941. How does the system become exposed to disease? What in¬ 
creases the danger of disease ? 

942. What power has man over the varieties of constitution ? What 
is the opinion of Thrackrah ? 

943. By what means are we to sustain health and prolong life ? 








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WORKS ON THE NATURAL SCIENCES. 


JARTIS’S PHYSIOLOGIES. 
PRACTICAL PHYSIOLOGY, 

FOR THE USE OF SCHOOLS AND FAMILIES. 


PRIMARY PHYSIOLOGY, 

FOR THE USE OF SCHOOLS 

The object of these works is to teach the Law of Life, and to fit persons 
to fulfil their responsibilities and to discharge the duties that come upon 
them in the management of their own bodies. 

It was not the design of the author to make children naturalists, or ana¬ 
tomists, or even physiologists merely, or in any way to give them mere 
barren learning; but he desired to teach them those facts and principles 
which would be profitable to them as guides in the discharge of their 
duties in their self-management. 

Every man is appointed to take charge of his own body; to supply its 
wants ; to appropriate his powers to their best purposes ; and thus to gain 
for himself the greatest advantage of health, strength, and enjoyment from 
the right management and use of his organs. 

It is therefore necessary that he should know the nature and character 
of thos-e organs ; their wants and powers ; how far they are submitted to 
his control; how far they may be affected by his management and use; 
and what is his duty in regard to them. 

Man is required to supply his stomach with food, and his lungs with air. 
He must clothe, bathe and protect his skin. He must make such use of 
his bones and muscles, and of his brain and nervous system as his health 
admits or requires. Beside these organs over which he has direct control, 
he can affect for good or for evil, the circulation of the blood, and the pre¬ 
paration of animal heat. 

In order to enable the pupils to perform these duties faithfully, the 
author of these works has described the general structure or anatomy of 
the stomach and the other parts of the digestive apparatus, of the lungs, 
the bones and muscles, the skin, and the brain and nervous system. 

In connection with these anatomical descriplions, the author has ex¬ 
plained more at length the actions, powers, wants and uses of these 
organs. And then he has shown extensively and minutely the relations 
of these organs and their actions to our own conduct, and to the external 

(78) 





JARVIS’S SERIES. 


world, and explained the law which should govern us in respect to our 
frames in all the varieties and details of life, showing the certain connec¬ 
tion between our fulfilment or neglect of duty in the supply of our wants 
and the use of our powers with health, strength, and comfort, or with 
sickness, weakness, and suffering. 

This connection between our self-management and health, in all the 
common contingencies, chances and affairs of life are so explained and illus¬ 
trated that any one, understanding these facts and principles, will know 
his duty and be thus prepared to avail himself of all the means of establish¬ 
ing and preserving his own powers, and of defending himself against the 
errors or chances that would diminish his fulness or enjoyment of life. 

These books, in the short time since they were first published, have 
gone through several editions. They are adopted in two of the Normal 
Schools in Massachusetts, in the Normal School of Connecticut, in the 
Public Schools of Baltimore, New Orleans, Roxbury, and Lowell, Mass., 
Cleveland and Sandusky City, Ohio, and extensively in schools and aca¬ 
demies throughout the United States. 

Among the very numerous testimonials from teachers and school com¬ 
missioners, and from public journals, which have been sent to the pub¬ 
lishers, are the following: 

From Hon. William B. Calhoun, Secretary of the State of Massachusetts. 

I have to thank you for your smaller work on Physiology. It is ex¬ 
tremity well adapted for the Common Schools, and I trust it will be exten¬ 
sively introduced, as well as your larger work. 

From George B. Emerson, Esq., of Boston, Member of the Board of Edu - 
cation, President of the American Institute of Instruction, and Teacher 
of a Private School for Females. 

I think highly of your book; I think it one of the best written and most 
satisfactory that I have seen upon the subject of Physiology. 1 have no 
doubt it will have the success which it eminently deserves. 

From Dr. Willard Parker, Professor of Surgery in the College of Phy» 
sicians and Surgeons in the City of New York. 

The Primary Physiology is clear and explicit, and admirably adapted to 
the comprehension of new beginners, and for use in Common Schools. 

The Practical Physiology is more extensive and full, and is written in 
a style that cannot fail to interest and attract those who wish to know 
something of the operations of life going on in “ the house they live in.” 
It contains important practical hints on the great object of Hygiene. 

Dr. Jarvis has conferred a favour upon his country ; and I hope we shall 
soon see Physiology making a part of the education of every youth, that 
he may be able to guard against the inroads of disease. 


(79) 




WORKS ON THE NATURAL SCIENCES. 


from. Dr. John C. Warren, of Boston, late Professor of Anatomy in Har• 

vard University. 

I nave examined with some care, Dr. Jarvis’s Practical Physiology. It 
is well adapted, by its accuracy, comprehensiveness, and the popular 
language in which it is expressed, to be a proper and valuable book for 
the purpose which it was designed to fulfil. 


From David S. Rowe, Esq., Principal of the State Normal School, West - 
field, Massachusetts. 

Though the treatises on this subject are so numerous, I think there is a 
general failure in the selections and arrangement of topics, or in not giving 
due prominence to those practical matters which constitute the chief value 
of a school book on Physiology. Some books give too minute instruction 
upon anatomy, and others do not afford a sufficiently distinct idea of the 
organs to render their functions intelligible. I think your book, to a great 
extent, avoids these defects. 


From Cyrus Peirce, late Principal Massachusetts Stale Normal School, 
West Newton, Mass. 

I have just taken a class through Jarvis’s Practical Physiology; I am 
pleased with it decidedly, and I shall continue to use it until I find eL/aie- 
thing better. I think it well adapted to schools and to families, being truly 
scientific, without the encumbrance of technical phraseology. The class 
seemed delighted with the work, and by an express vote declared it both 
entertaining and instructive. 


From Joseph Ray, M.D., Professor of Mathematics, Natural Philosophy 
and Chemistry, of Woodward College, Cincinnati, Ohio. 

I have examined with considerable care and much interest, a new work 
on Physiology for schools, &c., by Dr. Edward Jarvis. The subject of 
which it treats is of the highest importance to the happiness and well being 
of every individual; and should occupy a place in every system of edu¬ 
cation. 

The work of Dr. Jarvis is clear, intelligible, and interesting, and in my 
opinion, is well calculated for use, either as a text-book in schools, or as 
a reading book in families. 


From William H. Wells, Master of the Putnam School, Newburyport, 

Mass. 

The works which you have prepared appear to me exceedingly well 
adapted to meet the wants of schools in this department of instruction. 

( 80 ) 






JARVIS’S SERIES. 


From Dr. S. G. Howe, Director of the Perkins Institution for the Blind. 

Boston, Mass. 

The author has the rare gift of teaching sound philosophy in plain and 
simple language, and of illustrating it by striking examples easily compre¬ 
hended by the young. 

The laws and conditions of Physiology are clearly and beautifully illus¬ 
trated in Dr. Jarvis’s books ; they are not mere compilations of the words 
and thoughts of others, but they are full of just and instructive reflections, 
the result of careful study and thought. I hope the books may become 
widely known, for they must be greatly useful. 


From Thomas Seer win, A.M., Master of the High School for Boys, Boston, 
Your treatise meets a widely spread want in the community, and I am 
happy to recommend it to the entire public. 


From Mr. Charles Northend, Master of the Epes Grammar School, Sa r 

lem, Mass. 

I consider it a work of the highest merit. It is much better adapted to 
the wants of schools than any work on the same subject which I have ever 
seen. I sincerely hope that its appearance will greatly tend to increase the 
interest and attention of schools to the important subject of Physiology. 
It appears to me, that no individual can read your book without interest 
and profit. 

From Mr. Josiah A. Stearns, Master of the Mather School, Boston. 

It contains precisely the information needed by all classes of the com¬ 
munity. 

Rev. Addison Brown, Master of the Normal School, Bratileboro\ Vt., aiit ' 
County Superintendent of Public Schools. 

I have used your Physiology in my Normal School and Teachers’ In 
stitute. I have had my classes go through it pretty thoroughly and care¬ 
fully, and I am happy to say that the book gave entire satisfaction to the 
pupils and myself. I think it admirably adapted to the purpose for which 
it was written, and should rejoice to learn that it was studied in all out 
schools. It is written in an easy, clear style ; the arrangement is metho¬ 
dical ; the illustrations copious and to the purpose. 


From Rev. James Tufts, Superintendent of Schools, Windham County, Ft. 

As a book for family reading and information, I know of nothing to be 
compared with it. I have shown the work to several teachers, who prefe* 
U to any other work in use. 



































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